JP2017085780A - Dc power feeding system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DC power feeding system capable of performing stable power transfer in an emergency such as a disaster.SOLUTION: A DC power feeding system 100, at the normal time, supplies DC power to a home load 5 via a DC bus 30 mainly using both of power from a system power supply 1 and power from a photovoltaic power generation unit 2; and, at the time of outage of the system power supply 1, performs autonomous operation to supply DC power to the home load 5 via the DC bus 30 using at least one power supply unit of the photovoltaic power generation unit 2, an electric vehicle 3, and a battery unit 4. In the DC power feeding system 100, priority for a power supply unit for supplying power to be applied to the DC bus 30 at the time of the autonomous operation is set so that the priority is in order of the photovoltaic power generation unit 2, the electric vehicle 3, and the battery unit 4.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a DC power supply system that supplies power to a DC load using power from a plurality of power supply sources.

  Patent Document 1 below discloses a DC power supply system having a hybrid configuration using a solar power generation device, a first storage battery that is a vehicle-mounted storage battery, a second storage battery that is a low-voltage storage battery, and system power.

Japanese Patent No. 5290349

  However, in the DC power supply system of Patent Document 1 above, control of charge priority and control of discharge priority between the first storage battery and the second storage battery are not stipulated. There was a problem that stable power transfer could not be performed.

  The present invention has been made in view of the above, and an object of the present invention is to provide a DC power supply system that can perform stable power transfer even in an emergency such as a disaster.

  In order to solve the above-described problems and achieve the object, the DC power supply system according to the present invention normally uses the power from the system power supply and the power from the photovoltaic power generator mainly in combination through the DC bus. DC power is supplied to the DC load, and when the system power supply is interrupted, it is operated independently. DC power is supplied to the DC load using at least one of the photovoltaic power generation device, the portable power storage device, and the stationary power storage device. DC power is supplied through the bus. The DC power supply system converts the AC voltage applied from the system power source into a first DC voltage and applies it to the DC bus, and converts the DC voltage applied from the photovoltaic power generation device into the second DC voltage. A second power conversion unit that converts the voltage into a DC bus and converts the DC voltage applied from the portable power storage device into a third DC voltage and applies it to the DC bus; A third power conversion unit that charges the portable power storage device with a DC voltage applied via the unit or a DC bus, and converts a DC voltage applied from the stationary power storage device into a fourth DC voltage On the other hand, a fourth power conversion unit that charges the stationary power storage device with a DC voltage applied from another power conversion unit or a DC bus is provided. In the DC power supply system, the priority order of the power supply devices to be applied to the DC bus during the independent operation is set in the order of the photovoltaic power generation device, the stationary power storage device, and the portable power storage device.

  According to the present invention, there is an effect that stable power transfer can be performed even in an emergency such as a disaster.

1 is a block diagram showing a configuration of a DC power supply system according to Embodiment 1 The circuit diagram which shows the structure of the 3rd and 4th power converter shown in FIG. The flowchart explaining the operation | movement at the time of the self-sustained operation mode in the direct-current power supply system which concerns on Embodiment 1. Explanatory drawing about the threshold value used with the direct-current power supply system of Embodiment 3 Circuit diagram showing a configuration example of variable threshold in the DC power supply system of the third embodiment Block diagram showing a configuration of a DC power feeding system according to Embodiment 4 Block diagram showing a configuration of a DC power supply system according to Embodiment 5 The block diagram which shows the hardware constitutions of the control unit which controls the DC power supply system which concerns on Embodiment 1-5

  Hereinafter, a DC power supply system according to an embodiment of the present invention will be described with reference to the drawings. In addition, this invention is not limited by embodiment shown below.

Embodiment 1 FIG.
FIG. 1 is a block diagram illustrating a configuration of a DC power supply system according to the first embodiment. As shown in FIG. 1, a DC power supply system 100 according to Embodiment 1 normally includes power from a system power supply 1 that is a commercial power supply and a photovoltaic power generation apparatus that is one of a plurality of types of power supplies ( Photovoltaic power generation unit (hereinafter referred to as “PV” if necessary) 2) The power from the power source 2 is mainly used together to supply power to the in-house load 5; In addition to the power generation device 2, an electric vehicle (hereinafter referred to as “EV” if necessary) 3 and a battery unit (battery unit: hereinafter referred to as “ This is a system that supplies power to the home load 5 using at least one of the four). The home load 5 is a direct current load, and includes a lighting fixture, an air conditioner, a refrigerator, a microwave oven, a washing machine, a television, a personal computer, and the like.

  The solar power generation device 2 is an example of a power supply device that uses natural energy, and includes a solar cell 2a. The electric vehicle 3 is an example of a portable power storage device, and includes a hybrid electric vehicle. The electric vehicle 3 has a storage battery 3a. The storage battery unit 4 is an example of a stationary power storage device, and includes a lithium ion battery, a nickel hydrogen battery, a lead storage battery, or the like. The storage battery unit 4 has a storage battery 4a.

  Next, the configuration of DC power supply system 100 according to Embodiment 1 will be described. As illustrated in FIG. 1, the DC power supply system 100 according to the first embodiment includes a first power conversion unit 12, a second power conversion unit 16, and a third configuration configured to be able to supply DC power to the DC bus 30. The power converter 20 and the fourth power converter 24 are provided. The outputs of the second power conversion unit 16, the third power conversion unit 20, and the fourth power conversion unit 24 are configured to be applied to the DC bus 30 after being merged at the merge point 50.

  The first power conversion unit 12 has a function as an AC / DC converter, converts the AC voltage applied from the system power supply 1 into a first DC voltage, and applies it to the DC bus 30.

  The second power conversion unit 16 has a function as a DC / DC converter, converts the DC voltage applied from the solar battery 2 a of the solar power generation device 2 into a second DC voltage, and applies it to the DC bus 30. To do.

  The third power conversion unit 20 has a function as a bidirectional DC / DC converter, converts the DC voltage applied from the storage battery 3 a of the electric vehicle 3 into a third DC voltage, and applies the third DC voltage to the DC bus 30. On the other hand, the storage battery 3 a is charged with a DC voltage applied from another power conversion unit or the DC bus 30.

  The fourth power conversion unit 24 has a function as a bidirectional DC / DC converter, and converts a DC voltage applied from the storage battery 4a of the storage battery unit 4 into a fourth DC voltage, while other power conversions. The storage battery 4a is charged by a DC voltage applied from the unit or the DC bus 30.

  Further, the DC power supply system 100 according to the first embodiment is provided with a power failure detection circuit 10, a power generation amount detection circuit 14, battery capacity detection circuits 18, 22, a control power generation unit 26, and a control unit 28.

  The power failure detection circuit 10 detects a power failure of the system power supply 1 and transmits the detection result to the control unit 28. The power generation amount detection circuit 14 monitors the power generation amount of the solar power generation device 2 by detecting the output voltage and output current of the solar battery 2 a and transmits the monitoring result to the control unit 28. When the solar power generation device 2 has a power generation amount monitoring function, the power generation amount detection circuit 14 is unnecessary. The battery capacity detection circuit 18 monitors the remaining capacity or the state of charge (SOC) as the battery capacity of the storage battery 3 a and transmits the monitoring result to the control unit 28. When the electric vehicle 3 has a battery capacity monitoring function, the battery capacity detection circuit 18 is unnecessary. The battery capacity detection circuit 22 monitors the remaining capacity or the charging rate as the battery capacity of the storage battery 4 a and transmits the monitoring result to the control unit 28. When the storage battery unit 4 has a battery capacity monitoring function, the battery capacity detection circuit 22 is unnecessary.

  The control power supply generation unit 26 generates power for operating the control unit 28 with power supplied from the DC bus 30. The control unit 28 detects a power failure of the system power supply 1 based on the monitoring signal from the power failure detection circuit 10. When the control unit 28 detects a power failure of the system power supply 1, the control unit 28 switches the operation mode of the DC power supply system 100 from the grid interconnection operation mode to the independent operation mode. The DC power supply system 100 according to the present embodiment is characterized by the operation in the self-sustaining operation mode, and the control unit 28 determines the priority order of the power source supplied to the home load 5 in the self-sustaining operation mode. 2, the storage battery unit 4, and the electric vehicle 3. Further detailed operation in the self-sustaining operation mode will be described later. Further, the operation in the grid interconnection operation mode is known, and detailed description thereof is omitted here.

  Detailed configurations of the third power converter 20 and the fourth power converter 24 are as shown in FIG. The third power conversion unit 20 and the fourth power conversion unit 24 are configured to include a DC / DC conversion circuit 130 for operating as a bidirectional DC / DC converter. The DC / DC conversion circuit 130 converts a DC voltage applied from the storage battery side into an AC voltage internally, and then converts it again to a DC voltage and outputs it to the DC bus 30 side, or is applied from the DC bus 30. After the DC voltage to be converted into AC voltage is converted again to DC voltage and output to the storage battery side. That is, the DC / DC conversion circuit 130 performs an operation of mutually converting a DC voltage applied to the storage battery side and a DC voltage applied to the DC bus 30 side.

  As shown in FIG. 2, the DC / DC conversion circuit 130 has a symmetrical configuration with an insulating transformer 134 having windings 134a and 134b magnetically coupled therebetween. In the DC / DC conversion circuit 130, the switching elements 132a, 132b, 132c, and 132d are full-bridge connected, and the power conversion circuit 131 is connected to the winding 134a via the reactor 133, and the switching elements 138a, 138b, 138c, and 138d. Are connected to the winding 134b via the reactor 137, and the power conversion circuit 136 is configured. The power conversion circuit 131 is a DC / AC conversion circuit that converts a DC voltage applied from the DC bus 30 into an AC voltage and applies it to the winding 134a. The power conversion circuit 136 is a DC voltage applied from the storage battery side. Is a DC / AC conversion circuit that converts AC to AC voltage and applies it to the winding 134b. The DC / DC conversion circuit 130 configured as described above can freely step up and down the applied voltage from the DC bus 30 and the applied voltage from the storage battery side, and is an insulated voltage converter or power converter. Works as.

  A capacitor 120 for stabilizing the inter-terminal voltage is provided on the input / output terminal of the power conversion circuit 131, that is, on the DC bus 30 side of the DC / DC conversion circuit 130. The capacitor 120 is referred to as a first capacitor as necessary. Further, a capacitor 122 for stabilizing the inter-terminal voltage is connected to the input / output terminal of the power conversion circuit 136, that is, the storage battery side of the DC / DC conversion circuit 130. The capacitor 122 is referred to as a second capacitor as necessary.

  Next, the operation in the self-sustained operation mode in DC power supply system 100 according to Embodiment 1 will be described with reference to the drawings in FIGS. 1 and 3. FIG. 3 is a flowchart for explaining the operation of DC power supply system 100 according to Embodiment 1 in the self-sustaining operation mode. The process of each step shown in FIG. 3 is performed under the control of the control unit 28. In addition, in FIG. 3, the description of a code | symbol is abbreviate | omitted.

  First, as described above, a power failure of the system power supply 1 is detected by the power failure detection circuit 10 (step S101). For power failure detection, threshold determination can be used. For example, if the output voltage of the system power supply 1 is greater than or equal to a threshold value, it can be determined that there is no power failure, and if the output voltage of the system power supply 1 is less than the threshold value, it can be determined that there is a power failure. If it is determined in step S101 that no power failure is detected (No in step S101), the process in step S101 is repeated. On the other hand, when it is determined that a power failure has been detected (Yes in step S101), the operation mode is shifted to the independent operation mode (step S102), and power is supplied to the home load 5 in the independent operation mode (step S103).

  Next, the presence or absence of power generation at PV2 is detected by the power generation amount detection circuit 14 (step S104). A threshold determination can be used to detect the presence or absence of power generation. For example, if the output voltage of PV2 is greater than or equal to the threshold, it can be determined that PV2 is generating power, and if the output voltage of PV2 is less than the threshold, it can be determined that PV2 is not generating power. If it is determined in step S104 that PV2 is not generating power (No in step S104), the process proceeds to step S107 described later. On the other hand, when it is determined that PV2 is generating power (step S104, Yes), power supply from PV2 is started (step S105).

  Further, it is determined by the control unit 28 whether the power generation amount at PV2 is sufficient (step S106). A threshold value can be used to determine whether the power generation amount is sufficient or not. For example, the power generation amount detection circuit 14 detects the output voltage and output current of PV2 and transmits them to the control unit 28. The control unit 28 calculates the power generation amount from the output voltage and output current of PV2, and the calculated power generation amount Can be determined whether the amount of power generation is satisfied or not. In the determination process of step S106, when it is determined that the amount of power generated by PV2 is sufficient (step S106, Yes), the determination process of step S106 is repeatedly executed. On the other hand, when it is determined that the power generation amount at PV2 is not sufficient, that is, insufficient (step S106, No), power supply from BAT4 is started (step S107).

  Next, the battery capacity detection circuit 22 determines whether or not the battery capacity of the BAT 4 is sufficient (step S108). A threshold can be used to determine whether the battery capacity is satisfied or not. For example, by comparing the battery capacity of BAT4 with a threshold value, whether the battery capacity is satisfied or not can be determined. If it is determined in step S108 that the battery capacity of BAT4 is sufficient (Yes in step S108), the process in step S108 is repeatedly executed. On the other hand, when it is determined that the battery capacity of BAT4 is not sufficient, that is, insufficient (step S108, No), it is further determined whether EV3 is connected to the DC power supply system 100 (step S109). ).

  If EV3 is not connected to the DC power supply system 100 (No at Step S109), the process proceeds to Step S112 described later. On the other hand, if EV3 is connected to DC power supply system 100 (step S109, Yes), power supply from EV3 is started (step S110).

  Next, it is determined by the battery capacity detection circuit 18 whether or not the battery capacity of EV3 is sufficient (step S111). A threshold can be used to determine whether the battery capacity is satisfied or not. For example, by comparing the battery capacity of EV3 with a threshold value, whether the battery capacity is satisfied or not can be determined. If it is determined in step S111 that the battery capacity of EV3 is sufficient (Yes in step S111), the process in step S111 is repeatedly executed. On the other hand, when it is determined that the battery capacity of the EV 3 is not sufficient, that is, insufficient (step S111, No), the power supply to the home load 5 is terminated (step S112), and the flow of FIG. End.

  In the above-described processing, when power is supplied to the home load 5 from one power supply device, that is, a priority power supply device, power supply from other power supply devices is not performed. More specifically, when power is supplied from PV2, power supply from EV3 and BAT4 is stopped, and when power is supplied from BAT4, power supply from PV2 and EV3 is stopped. When power is supplied from EV3, the power supply from PV2 and BAT4 is stopped. The stop of power supply is controlled by the control unit 28 under the control of the corresponding power converter, that is, the second power converter 16 in the case of PV2, the third power converter 20 in the case of EV3, and the BAT4. In some cases, this can be realized by stopping the operation of the fourth power converter 24.

  As described above, according to the DC power supply system 100 according to the first embodiment, when a power failure of the system power supply 1 is detected and the self-sustaining operation is started, the solar power generation device 2 that is a power supply device that uses natural energy. In addition, output control is performed with priority on the electric vehicle 3 that is a portable power storage device and the storage battery unit 4 that is a stationary power storage device. The priority order is the order of the solar power generation device 2, the storage battery unit 4, and the electric vehicle 3.

  That is, when shifting to the self-sustained operation mode, first, the power from the solar power generation device 2 having the first priority, that is, the highest priority is supplied to the home load 5. Next, when the output of the photovoltaic power generation device 2 cuts the threshold, the next priority, that is, the priority is switched to the output of the storage battery unit 4, and the power from the storage battery unit 4 is transferred to the home load 5. Supply. Further, when the output of the storage battery unit 4 falls below the threshold value, the next priority, that is, the priority is switched to the output of the third electric vehicle 3, and the electric power from the electric vehicle 3 is supplied to the residential load 5.

  As described above, the DC power supply system according to Embodiment 1 includes a solar power generation device that is a power supply device that uses natural energy, a storage battery unit that is a stationary power storage device, and a portable power storage device. Prioritize multiple types of power supply devices including electric vehicles, and switch to the next highest priority power supply according to a command from the control unit when the output of the power supply device with high priority reaches the judgment threshold I have to. By using the solar power generation device preferentially, the deterioration of the storage battery unit, which is a stationary power storage device, due to charging and discharging of the storage battery is suppressed, and this control uses up the power of the solar power generation device and the stationary storage battery unit. Even in such a case, since the power of the portable electric vehicle can be used, stable power transfer can be performed even in an emergency such as a disaster.

  Moreover, according to the DC power supply system according to the first embodiment, the priority order of the power supplied to the residential load in the self-sustaining operation mode is set in the order of the photovoltaic power generation device, the storage battery unit, and the electric vehicle. It becomes possible to leave the electric power of the highly convenient electric vehicle and to secure the travel distance of the electric vehicle as the moving means.

  In addition, according to the DC power supply system according to the first embodiment, the operation of the power conversion unit connected to the power supply device other than the priority power supply device is stopped, so that unnecessary standby power can be reduced. This can save energy.

Embodiment 2. FIG.
In the first embodiment, when power is supplied from a power supply apparatus that prioritizes power supply to the home load, the operation of the power conversion unit connected to the other power supply apparatus is stopped. In 2, the operation of the power conversion unit is not stopped, and a similar function is realized by controlling the output command voltage to the power conversion unit. Hereinafter, the DC power supply system according to Embodiment 2 will be described. The system configuration is the same as or equivalent to that of the first embodiment.

  In the second embodiment, the output command voltage for the power conversion unit connected to the priority power supply apparatus is set larger than the output command voltage for the power conversion unit connected to the non-priority power supply apparatus. More specifically, when power is supplied from PV2, the output command voltage for the power converter connected to PV2 is made larger than the output command voltage for the power converter connected to EV3 and BAT4. If controlled in this way, the electric power is supplied to the home load 5 from the PV 2 having the largest output command voltage. When power is supplied from BAT4, the output command voltage for the power converter connected to BAT4 is set larger than the output command voltage for the power converter connected to PV2 and EV3. By controlling in this way, the electric power supplied to the home load 5 is supplied from the BAT 4 having the largest output command voltage.

  As described above, according to the DC power supply system according to the second embodiment, output control according to the priority order can be performed without stopping the operation of the power conversion unit, so that the switching of the power supply apparatus can be performed smoothly and reliably. It can be carried out.

Embodiment 3 FIG.
In the first embodiment and the second embodiment, the power supply to the home load 5 is performed by only one power supply device. However, in the third embodiment, the power supply to the home load 5 is performed by a plurality of power supplies. It is modified so that it can be performed by the power supply device. Hereinafter, the DC power supply system according to Embodiment 3 will be described with reference to FIGS. 4 and 5. The system configuration is the same as or equivalent to that of the first embodiment.

  FIG. 4 is an explanatory diagram of threshold values used in the DC power supply system according to the third embodiment. FIG. 4 shows four threshold values from the first threshold value to the fourth threshold value. In the first embodiment, the determination of whether or not the power generation amount in PV2 is satisfied / not satisfied is made using a one-step threshold value (see step S106 in FIG. 3). However, in the third embodiment, the first threshold value and , A two-stage threshold value, a second threshold value that is smaller than the first threshold value, is used. More specifically, when the power generation amount of PV2 is equal to or greater than the first threshold, power is supplied to the home load 5 using only the output of PV2. On the other hand, if the power generation amount of PV2 decreases and the power generation amount of PV2 is less than the first threshold value and greater than or equal to the second threshold value, the power supply to the home load 5 is performed using the output of PV2 and the output of BAT4 in combination. If the power generation amount of PV2 becomes less than the second threshold value, the output of PV2 is stopped, and the power supply to the home load 5 is performed only by the output of BAT4.

  Further, when the power generation amount of PV2 is reduced, in the first embodiment, the determination of whether the power generation amount in BAT4 is satisfied / not satisfied is made using a one-step threshold (see step S108 in FIG. 3). In the third embodiment, a two-stage threshold value is used which is a third threshold value and a fourth threshold value that is smaller than the third threshold value. More specifically, when the power generation amount of the BAT 4 is equal to or greater than the third threshold value, the power supply to the home load 5 is performed using only the output of the BAT 4. On the other hand, if the power generation amount of BAT4 decreases and the power generation amount of BAT4 is less than the third threshold value and greater than or equal to the fourth threshold value, the power supply to the home load 5 is performed using both the output of BAT4 and the output of EV3. In addition, if the power generation amount of BAT4 becomes less than the fourth threshold, the output of BAT4 is stopped, and the electric power is supplied to the home load 5 only by the output of EV3.

  In FIG. 4, the case where two threshold values are used for determining whether the power generation amount is sufficient or not in PV2 and BAT4 is illustrated, but three or more threshold values may be used. For example, assuming that there are two stationary storage battery units, when the PV2 power generation amount falls below the initial threshold, in addition to the PV2 output, one of the storage battery units is used in combination to supply power. When the power generation amount of PV2 falls below the second threshold value, in addition to the output of PV2, power is supplied using two storage battery units together, and when the power generation amount falls below the third threshold value, two units It is possible to operate such that power is supplied only by the storage battery unit.

  Further, in FIG. 4, the case where the power generation amount of PV2 decreases and then increases again (hereinafter referred to as “regeneration”) is not considered, but the PV2 regeneration may be considered. For example, if the power generation amount of PV2 drops and the second threshold is cut off, then the power is regenerated and the power generation amount of PV2 exceeds the first threshold, the power supply from BAT4 or EV3 is stopped and PV2 What is necessary is just to restart the power supply from.

  FIG. 5 is a circuit diagram showing a configuration example of variable threshold in the DC power supply system according to the third embodiment. 5, the same or equivalent components as shown in FIGS. 1 and 2 are denoted by the same reference numerals.

  In FIG. 5, resistance elements 124 and 126 connected in series are connected in parallel to both ends of a capacitor 120 located on the DC bus 30 side of the DC / DC conversion circuit 130. The divided voltage by the resistance elements 124 and 126 is applied to the plus terminal of the comparator 110, and the output voltage of the reference voltage generating means 112 is applied to the minus terminal of the comparator 110. The output voltage of the reference voltage generation means 112 is configured to be changed by control from the control unit 28. Changing the output voltage of the reference voltage generation unit 112 corresponds to changing the threshold value described above. The comparison result of the comparator 110 is input to the control unit 28. The control unit 28 controls the output voltage of the DC / DC conversion circuit 130 based on the comparison result of the comparator 110.

  As described above, according to the direct current power supply system according to the third embodiment, the switching determination of the power supply device is performed using at least two threshold levels, so that the output of the power supply device is switched while being overlapped. As compared with the second embodiment, the switching of the power supply device can be further facilitated.

Embodiment 4 FIG.
FIG. 6 is a block diagram showing a configuration of a DC power supply system according to Embodiment 4. In FIG. In the first to third embodiments, the configuration in which the outputs of the second power converter 16, the third power converter 20, and the fourth power converter 24 are directly connected to the DC bus 30 has been disclosed. On the other hand, in the fourth embodiment, the second power conversion unit 16, the third power conversion unit 20, and the fourth power conversion unit 24, the second power conversion unit 16, and the third power conversion unit 20, respectively. In addition, a configuration is disclosed in which each of the diodes 31, 32b, and 34b as backflow prevention elements is provided between the output confluence 50 and the fourth power conversion unit 24. In FIG. 6, the same or equivalent components as those shown in FIG. 1 are denoted by the same reference numerals.

  In the DC power supply system according to the second embodiment, the operation of the second power converter 16, the third power converter 20, or the fourth power converter 24 is not stopped, and the output command to the corresponding power converter By controlling the voltage, power supply from a desired power supply device is realized. As described above, the output voltage of the power conversion unit connected to the power supply apparatus with a high priority is set higher than the output voltages of the other two power conversion units with low priority. For this reason, in the configuration of FIG. 1, the capacitor 120 (see FIGS. 2 and 5) provided at the input / output ends of the other two power conversion units is charged. In order to prevent this charging, diodes 31, 32b and 34b are provided at the output stage of each power converter so that the cathode faces the DC bus 30 side. With this configuration, even when the output voltage of the power conversion unit connected to the power supply device with high priority is set to a high value, the output voltage is lowered from the power conversion unit set to a high output voltage. Since the flow of power to the power conversion unit set to, that is, the backflow is prevented, unnecessary charging of the capacitor 120 provided at the input / output end can be suppressed. With this configuration, energy can be effectively used, and energy saving can be achieved. Further, since unnecessary charging of the capacitor 120 can be suppressed, the life of the capacitor 120 can be extended.

  In the configuration of FIG. 6, the storage battery 3a of the electric vehicle 3 cannot be charged only by the diode 32b. For this reason, the transistor 32a that can charge the storage battery 3a is connected in antiparallel to both ends of the diode 32b. The element configuration in which the transistor 32a and the diode 32b are connected in antiparallel is the same as the switching element used in the power conversion circuit illustrated in FIG. 2 and can be configured using the switching element 32.

  Similarly, in the configuration of FIG. 6, the storage battery 4a of the storage battery unit 4 cannot be charged only by the diode 34b. Therefore, the transistor 34a that enables the storage battery 4a to be charged is connected in antiparallel to both ends of the diode 34b. ing. The element configuration in which the transistor 34a and the diode 34b are connected in antiparallel is the same as the switching element used in the power conversion circuit illustrated in FIG. 2 and can be configured using the switching element 34. When the switching element 32 and the switching element 34 are distinguished without reference numerals, the switching element 32 is referred to as a “first switching element” and the switching element 34 is referred to as a “second switching element”.

  As described above, according to the DC power feeding system according to the fourth embodiment, the outputs of the second, third, and fourth power conversion units and the outputs of the second, third, and fourth power conversion units, respectively. Since a diode as a backflow prevention element is provided between the junction points, unnecessary charging of the capacitor provided at the input / output terminal of the power conversion unit can be suppressed. In addition, since unnecessary charging of the capacitor can be suppressed, energy can be used effectively and energy saving can be achieved. Furthermore, since unnecessary charging to the capacitor provided at the input / output terminal of the power conversion unit can be suppressed, the life of the capacitor can be extended.

Embodiment 5. FIG.
In the first embodiment, the power supply to the home load is controlled by stopping the operation of the power conversion unit connected to the power supply device having a low priority. Further, in the second embodiment, the function similar to that of the first embodiment is realized by controlling the output command voltage to the power conversion unit without stopping the operation of the power conversion unit. On the other hand, the fifth embodiment discloses a configuration that can freely control power supply to the home load without stopping the operation of the power conversion unit and without providing a difference in the output command voltage to the power conversion unit. To do. Hereinafter, a DC power supply system according to Embodiment 5 will be described with reference to the drawing of FIG.

  FIG. 7 is a block diagram showing a configuration of a DC power supply system according to Embodiment 5. In FIG. DC power supply system 100 according to Embodiment 5 shown in FIG. 7 has a configuration in FIG. 6, in which switching element 36 is inserted between third power conversion unit 20 and switching element 32, and fourth power conversion unit The switching element 38 is inserted between the switching element 34 and the switching element 34. In addition, about another structure, it is the same as that of Embodiment 4 shown in FIG. 6, or is equivalent, The same code | symbol is attached | subjected and shown to those common components, and the overlapping description is abbreviate | omitted. Further, when the switching element 36 and the switching element 38 are distinguished without reference numerals, the switching element 36 is referred to as “third switching element”, and the switching element 38 is referred to as “fourth switching element”.

  The switching element 36 connected between the third power conversion unit 20 and the switching element 32 has the same configuration as the switching element 32, and includes a diode 36b and a transistor 36a connected in antiparallel to both ends of the diode 36b. And is configured. However, while the switching element 32 is connected in a direction that prevents charging of the storage battery 3a of the electric vehicle 3, the switching element 36 is connected in a direction that prevents discharge from the storage battery 3a. The diode 32b of the switching element 32 operates as a backflow prevention element, whereas the diode 36b of the switching element 36 operates as a discharge prevention element. In order to discharge the storage battery 3a, the transistor 36a of the switching element 36 may be controlled to be on.

  The switching element 38 connected between the fourth power conversion unit 24 and the switching element 34 has the same configuration as the switching element 34, and is connected in antiparallel to both ends of the diode 38b and the diode 38b. And a transistor 38a. However, while the switching element 34 is connected in a direction that prevents charging of the storage battery 4a of the storage battery unit 4, the switching element 38 is connected in a direction that prevents discharge from the storage battery 4a. The diode 34b of the switching element 34 operates as a backflow prevention element, whereas the diode 38b of the switching element 38 operates as a discharge prevention element. In order to discharge the storage battery 4a, the transistor 38a of the switching element 38 may be controlled to be turned on.

  By providing the switching element 36, the discharge from the storage battery 3 a can be suppressed by controlling the transistor 36 a to be turned off without stopping the operation of the third power conversion unit 20. In addition, by providing the switching element 38, it is possible to suppress the discharge from the storage battery 4a by controlling the transistor 38a to be off without stopping the operation of the fourth power conversion unit 24. Note that since the power supply to the DC bus 30 can be controlled by controlling the transistors 36a and 38a, the control of the output command voltage to the power conversion unit performed in the second embodiment is unnecessary.

  As described above, according to the DC power feeding system according to the fifth embodiment, the diode as the discharge prevention element is provided between the first switching element including the diode as the backflow prevention element and the third power conversion unit. And a third switching element including a diode as a discharge prevention element is provided between the second switching element including a diode as a backflow prevention element and the fourth power converter. Therefore, the discharge from the portable storage battery can be suppressed without stopping the operation of the third power conversion unit, and the stationary type can be performed without stopping the operation of the fourth power conversion unit. Discharge from the storage battery can be suppressed. Furthermore, since the power supply to the DC bus can be controlled by performing the conduction control to the third and fourth switching elements, the control of the output command voltage to the power conversion unit can be made unnecessary.

  Finally, the hardware configuration of the control unit 28 that controls the DC power supply system 100 according to the first to fifth embodiments will be described. FIG. 8 is a block diagram showing a hardware configuration of the control unit 28. As shown in FIG. 8, the control unit 28 functions as a CPU (Central Processing Unit) 28a that performs computations, and a memory 28b that stores programs read by the CPU 28a, and inputs and outputs signals. It can be realized by the interface 28c.

  Specifically, a program for executing the function of the control unit 28 is stored in the memory 28b. The CPU 28a receives the monitoring signal from the power failure detection circuit 10 and the detection signals from the power generation amount detection circuit 14 and the battery capacity detection circuits 18 and 22 via the interface 28c. The CPU 28a generates a signal for on / off control of the switching elements of the second power converter 16, the third power converter 20, or the fourth power converter 24 based on the monitoring signal and the detection signal. And output to the corresponding power converter through the interface 28c.

  When charging the storage battery 3a of the electric vehicle 3, the CPU 28a generates a control signal for turning on the transistor 32a of the switching element 32, and applies the control signal to the gate of the transistor 32a via the interface 28c.

  When the storage battery 4a of the storage battery unit 4 is charged, the CPU 28a generates a control signal for turning on the transistor 34a of the switching element 34, and applies the control signal to the gate of the transistor 34a via the interface 28c.

  When discharging the storage battery 3a of the electric vehicle 3, the CPU 28a generates a control signal for turning on the transistor 36a of the switching element 36, and applies the control signal to the gate of the transistor 36a via the interface 28c.

  When the storage battery 4a of the storage battery unit 4 is discharged, the CPU 28a generates a control signal for turning on the transistor 38a of the switching element 38, and applies the control signal to the gate of the transistor 38a via the interface 28c.

  Note that the configurations shown in the above embodiments are examples of the contents of the present invention, and can be combined with other known techniques, and can be combined without departing from the gist of the present invention. It is also possible to omit or change a part of.

  1 system power supply, 2 solar power generation device, 2a solar battery, 3 electric vehicle, 3a storage battery, 4 storage battery unit, 4a storage battery, 5 load in house, 10 power failure detection circuit, 12 first power converter (AC / DC converter) , 14 Power generation amount detection circuit, 16 Second power conversion unit (DC / DC converter), 18, 22 Battery capacity detection circuit, 20 Third power conversion unit (bidirectional DC / DC converter), 24 Fourth power Conversion unit (bidirectional DC / DC converter), 26 control power generation means, 28 control unit, 28a CPU, 28b memory, 28c interface, 30 DC bus, 31 diode (backflow prevention element), 32 switching element (first switching) Element), 32a transistor, 32b diode (backflow prevention element), 34 switching element Child (second switching element), 34a transistor, 34b diode (backflow prevention element), 36 switching element (third switching element), 36a transistor, 36b diode, 38 switching element (fourth switching element), 38a transistor , 38b diode, 50 junction, 100 DC power supply system, 110 comparator, 112 reference voltage generating means, 120 capacitor (first capacitor), 122 capacitor (second capacitor), 124, 126 resistance element, 130 DC / DC Conversion circuit, 131, 136 Power conversion circuit (DC / AC conversion circuit), 132a, 132b, 132c, 132d, 138a, 138b, 138c, 138d Switching element, 133, 137 reactor, 134 Transformer, 134a, 134b Winding.

In order to solve the above-described problems and achieve the object, the DC power supply system according to the present invention normally uses the power from the system power supply and the power from the photovoltaic power generator mainly in combination through the DC bus. DC power is supplied to the DC load, and when the system power supply is interrupted, it is operated independently. DC power is supplied to the DC load using at least one of the photovoltaic power generation device, the portable power storage device, and the stationary power storage device. DC power is supplied through the bus. Furthermore, the DC power supply system according to the present invention is applied from a first power conversion unit that converts an AC voltage applied from a system power source into a first DC voltage and applies it to a DC bus, and is applied from a solar power generation device. applied to the DC bus DC voltage by converting the second power conversion unit for applying a second DC bus into a DC voltage, the DC voltage applied from the power storage device of a portable to a third DC voltage while, the third power conversion unit for charging the power storage device of a portable by the DC voltage applied through the other of the power conversion unit or DC bus, the DC voltage applied from a stationary power storage device first while converting the fourth DC voltage, and a fourth power converter for charging a stationary power storage device by the DC voltage applied from another power converting unit or DC bus. Further, the DC power supply system according to the present invention, during self-sustained operation, the priority of the power supply applied to the DC bus, photovoltaic devices, stationary power storage device, is set in the order of a portable power storage device, When the power generation amount of the solar power generation device, the battery capacity of the stationary power storage device, and the battery capacity of the portable power storage device are determined as threshold values according to the priority order, and the power generation amount of the solar power generation device is equal to or greater than the first threshold value The power supply to the DC load is performed only by the output of the solar power generation device, the power generation amount of the solar power generation device is reduced, the power generation amount of the solar power generation device is less than the first threshold, and the first If it is equal to or greater than a second threshold value that is smaller than the threshold value, power is supplied to the DC load using both the output of the photovoltaic power generation device and the output of the stationary power storage device, and the power generation of the stationary power storage device If the amount is greater than or equal to the third threshold, The power supply to the DC load is performed only by the output of the device, the power generation amount of the stationary power storage device is reduced, and the power generation amount of the stationary power storage device is less than the third threshold value and is greater than the third threshold value. If the power is not less than the fourth threshold value, the output of the stationary power storage device and the output of the portable power storage device are used together to supply power to the DC load, and the power generation amount of the stationary power storage device is If it is less than the threshold value of 4, power is supplied to the DC load only by the output of the portable power storage device.

Claims (7)

In normal times, the power from the system power supply and the power from the photovoltaic power generator are mainly used together to supply DC power to the DC load via the DC bus. A DC power supply system that supplies DC power to the DC load via the DC bus using at least one power source device of a photovoltaic power generation device, a portable power storage device, and a stationary power storage device,
A first power conversion unit that converts an AC voltage applied from the system power supply into a first DC voltage and applies the DC voltage to the DC bus;
A second power converter that converts a DC voltage applied from the solar power generation device into a second DC voltage and applies the second DC voltage to the DC bus;
While converting the DC voltage applied from the portable power storage device into a third DC voltage and applying it to the DC bus, the DC voltage applied via another power converter or the DC bus A third power converter for charging the portable power storage device;
A DC voltage applied from the stationary power storage device is converted into a fourth DC voltage, while the stationary power storage device is charged by a DC voltage applied from another power converter or a DC bus. And a power conversion unit of
The DC power supply system in which the priority order of the power supply device applied to the DC bus during the independent operation is set in the order of the solar power generation device, the stationary power storage device, and the portable power storage device.   The DC power feeding system according to claim 1, wherein during the self-sustained operation, the operation of the power conversion unit connected to a power supply device other than the power supply device having priority is stopped.   The output command voltage for the power conversion unit connected to the priority power supply device is set to be larger than the output command voltage for the power conversion unit connected to the non-priority power supply device during the independent operation. DC power supply system.   A diode as a backflow prevention element is provided between each of the second, third, and fourth power conversion units and a junction of outputs from the second, third, and fourth power conversion units. The DC power supply system according to claim 3. A diode as a backflow prevention element is provided between the second power conversion unit and a junction of outputs from the second, third, and fourth power conversion units,
A first switching element including a diode as a backflow prevention element is provided between the third power conversion unit and the junction, and between the fourth power conversion unit and the junction. A second switching element including a diode as a backflow prevention element is provided;
A third switching element including a diode as a discharge preventing element is provided between the first switching element and the third power conversion unit, and the second switching element and the fourth power conversion are provided. The DC power feeding system according to claim 1, wherein a fourth switching element including a diode as a discharge preventing element is provided between the first and second sections.   According to the priority order, the power generation amount of the photovoltaic power generation device, the battery capacity of the portable power storage device and the battery capacity of the stationary power storage device are determined as threshold values, and the power supply device is switched based on the threshold determination. The DC power supply system according to any one of claims 1 to 5, wherein the DC power supply system is performed.   The DC power supply system according to claim 6, wherein the threshold determination is performed using at least two stages of thresholds when the power supply apparatus is switched based on the threshold determination.

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