Power systems and refrigeration systems

Abstract

This approach allows for suppression of inrush current while minimizing the increase in the size of the power converter, compared to a system where the power converter is equipped with a function to prevent inrush current. [Solution] The power system 1 includes a grid-connected inverter 12 capable of mutually converting AC power from an AC power source 30 and DC power from a DC bus line 51, a power conditioner 10 equipped with a smoothing capacitor 13 connected to the DC bus line 51, a rectifier 64 that converts AC power to DC power, a surge protection circuit 61 provided between the DC bus line 51 and the rectifier 64, or between the rectifier 64 and the AC power source 30, and a hybrid device 60 that can operate by receiving DC power from the DC bus line 51 or DC power from the rectifier 64. When the voltage across the smoothing capacitor 13 is less than a predetermined value, the smoothing capacitor 13 is charged via the surge protection circuit, and then the hybrid device 60 is made to operate.

Description

Technical Field

[0001] The present disclosure relates to a power system and a refrigeration system.

Background Art

[0002] In Patent Document 1, in a system in which an AC power supply, a solar cell, a control unit, a battery, and a DC distribution board are connected, a power distribution device that extracts power from the solar cell by controlling the operation of a first converter based on a command signal from a control unit has been proposed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the power distribution device of Patent Document 1, when supplying power from the AC power supply to the DC distribution board when the line voltage of the AC power supply is greater than the line voltage between the DC power lines, an inrush current may flow and there is a risk of damaging the equipment. However, no countermeasures against the inrush current are considered. An object of the present disclosure is to suppress an inrush current while suppressing an increase in the size of a power converter as compared with a case where a function for preventing an inrush current is provided in the power converter.

Means for Solving the Problems

[0005] The first aspect of the power system is a power converter comprising an inverter configured to mutually convert AC power from an AC power source and DC power from a DC bus line, and a smoothing capacitor connected to the DC bus line; an AC / DC converter that converts AC power from the AC power source into DC power; an inrush current prevention circuit provided between the DC bus line and the AC / DC converter, or between the AC / DC converter and the AC power source; and a DC device that can operate by receiving DC power from the DC bus line or DC power from the AC / DC converter, wherein if the voltage across the smoothing capacitor is less than a predetermined value, the smoothing capacitor is charged via the inrush current prevention circuit before the DC device is put into operation. This power system allows for the utilization of the inrush current prevention function built into the equipment connected to the DC bus line of the power converter, without requiring the power converter to have its own inrush current prevention function. Compared to a system where the power converter has its own inrush current prevention function, this system suppresses inrush current while keeping the size of the power converter under control.

[0006] The power system from the second perspective is one in which, in the power system from the first perspective, the DC equipment, the AC / DC converter, and the inrush current prevention circuit constitute an electrical device capable of receiving DC power and AC power and operating. This power system can supply power to electrical equipment that can operate using both direct current and alternating current.

[0007] The power system in the third aspect is the power system in the second aspect, wherein two or more electrical devices are connected to the DC bus line, and when an operation command is received for the first electrical device, the smoothing capacitor is charged via the inrush current prevention circuit provided in the second electrical device. This power system allows for the selection of the appropriate inrush current protection circuit from two or more options, thereby increasing reliability.

[0008] In the fourth aspect of the power system, in any of the first to third aspects of the power system, the inrush current prevention circuit charges the smoothing capacitor based on the operation command to the DC equipment. This power system allows for control of charging in response to operational commands.

[0009] The power system of the fifth aspect is such that, in any of the power systems of the first to fourth aspects, when an operation command is received for the DC equipment, the smoothing capacitor is charged via the inrush current prevention circuit, and then the DC equipment is made to operate. This power system allows for control of operations in response to operational commands.

[0010] The power system of the sixth aspect is a power system of any of the first to fifth aspects, wherein the DC equipment further comprises detection means for detecting the voltage of the DC bus line, and when an operation command is received for the DC equipment, if the voltage detected by the detection means is less than a predetermined value, the smoothing capacitor is charged via the inrush current prevention circuit and then the DC equipment is made to operate. This power system allows for control based on the detected voltage value of the DC bus line.

[0011] The power system of the seventh aspect is the power system of the second aspect, wherein the DC equipment further comprises detection means for detecting the voltage of the DC bus line, and when an operation command is received for the DC equipment, if the voltage detected by the detection means is greater than or equal to a predetermined value, the electrical equipment is made to operate without charging the smoothing capacitor. This power system allows for control based on the detected voltage value of the DC bus line.

[0012] The power system of the eighth aspect, in any of the power systems of the first to seventh aspects, when an operation command is received for the DC equipment, charges the smoothing capacitor via the inrush current prevention circuit and then connects the power converter to the grid.

[0013] The power system of the ninth aspect is one in which, in any of the power systems of the first to eighth aspects, the AC / DC converters and the DC equipment are connected to the DC bus line, and the number of AC / DC converters is less than the number of DC equipment. This power system can accommodate situations where electrical equipment capable of receiving both DC and AC power is connected, as well as electrical equipment capable of receiving only DC power.

[0014] The power system of the tenth aspect includes a DC / DC converter in the DC bus line connecting the power converter and the DC equipment, in any of the power systems of the first to ninth aspects. This power system allows for limiting the current flowing through the DC bus line connecting the power converter and DC equipment. As a result, when operating only DC equipment without using the power converter, limiting the current flowing through the DC bus line reduces the power required to charge the power converter and the standby power consumption.

[0015] The power system of the eleventh aspect includes a DC / DC converter configured to convert between the DC power of a DC power source and the DC power of the DC bus line, in any of the power systems of the first to tenth aspects. According to this power system, DC power supplied from a DC power source can be boosted or bucked as needed and supplied to a DC bus line.

[0016] Furthermore, the refrigeration system of the twelfth aspect is a refrigeration system having a refrigeration device as a DC device of the first aspect. This refrigeration system allows for the utilization of the inrush current prevention function built into the refrigeration unit connected to the DC bus line of the power converter, without requiring the power converter to have its own inrush current prevention function. Compared to a system where the power converter supplying DC power to the refrigeration unit has its own inrush current prevention function, this system suppresses inrush current while keeping the size of the power converter under control. [Brief explanation of the drawing]

[0017] [Figure 1] It is a diagram showing an example of the overall configuration of a power system to which the first embodiment is applied. [Figure 2] It is a diagram showing an example of the overall configuration of a power system to which the second embodiment is applied. [Figure 3] It is a diagram showing an example of the overall configuration of a power system to which the third embodiment is applied. [Figure 4] It is a diagram showing an example of the overall configuration of a power system to which the fourth embodiment is applied. [Figure 5] It is a diagram showing an example of the overall configuration of a power system to which the fifth embodiment is applied. [Figure 6] It is a diagram showing an example of the overall configuration of a power system to which the sixth embodiment is applied. [Figure 7] It is a diagram showing an example of the overall configuration of a power system to which the seventh embodiment is applied.

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. <The First Embodiment> [Overall Configuration] FIG. 1 is a diagram showing an example of the overall configuration of a power system 1 to which the first embodiment is applied. The power system 1 shown in FIG. 1 has an electric device (hereinafter referred to as a "hybrid device") 60 that can receive DC power and AC power, connected to a DC bus line 51 that supplies DC power and an AC line 50 that supplies AC power. Further, the power system 1 has a power conditioner 10 as a power converter that can supply DC power to the DC bus line 51. The power conditioner 10 includes a DC / DC converter 11, a grid-connected inverter 12, and a grid-connected relay 14. The DC bus line 51 is a power line with one end connected to the DC / DC converter 11 and the other end connected to the grid-connected inverter 12.

[0019] The DC / DC converter 11 is a converter that boosts or bucks the DC power supplied from the solar panel 40, which is a DC power source, as needed, and supplies it to the DC bus line 51. The grid-connected inverter 12 is an inverter configured to mutually convert AC power from the AC power source 30 and DC power from the DC bus line 51. The grid-connected inverter 12 does not have an inrush current prevention circuit (hereinafter abbreviated as "inrush current prevention circuit") that has a function to prevent inrush current. The grid-connected inverter 12 is equipped with a diode that energizes when the DC voltage value of the DC bus line 51 is lower than the AC voltage value of the AC line 50, allowing current to flow from the AC line 50 to the DC bus line 51.

[0020] The power conditioner 10 includes a smoothing capacitor 13 connected to a DC bus line 51. The smoothing capacitor 13 begins charging upon receiving DC power from the DC bus line 51. Subsequently, the voltage value of the smoothing capacitor 13 gradually increases and approaches the voltage value of the DC bus line 51. The smoothing capacitor 13 stabilizes the voltage value of the DC bus line 51 by absorbing the pulsating current from the rectifier 64 of the hybrid device 60 (described later) and reducing voltage fluctuations. When the smoothing capacitor 13 is fully charged, the voltage value of the DC bus line 51 stabilizes at a predetermined target value.

[0021] Here, the hybrid device 60 also has a smoothing capacitor 63, but the smoothing capacitor 13 of the power conditioner 10 and the smoothing capacitor 63 of the hybrid device 60 are electrically connected to a common DC bus line 51. Therefore, when the smoothing capacitor 13 of the power conditioner 10 is charged, the smoothing capacitor 63 of the hybrid device 60 is also charged. The capacitance of the smoothing capacitor 13 is designed according to the power demand and the allowable range of voltage fluctuations in the power system 1.

[0022] The hybrid equipment 60 includes a load 67, which consists of a motor. For example, if the hybrid equipment 60 is a refrigeration system, the power system 1 can also be considered as a refrigeration system comprising the refrigeration system as the hybrid equipment 60. In this case, the load 67 functions as an electric motor that drives a compressor, fan, etc.

[0023] Furthermore, the hybrid device 60 includes a DC / AC inverter 62 that converts DC power into AC power suitable for driving the load 67. The hybrid device 60 also includes a smoothing capacitor 63 that contributes to the stable operation of the load 67 and the DC / AC inverter 62 by smoothing voltage fluctuations.

[0024] The hybrid device 60 also includes a rectifier 64. The rectifier 64 functions as an AC / DC converter, converting AC power from the AC power source 30 into DC power. Specifically, the rectifier 64 rectifies the AC power from the AC line 50 into pulsating DC. In addition, when the smoothing capacitor 13 of the power conditioner 10 is charged, the rectifier 64 rectifies the positive and negative fluctuations of the AC current and converts them into DC current.

[0025] Furthermore, the hybrid device 60 is equipped with a surge protection circuit 61 to prevent inrush current. The surge protection circuit 61 is provided between the DC bus line 51 and the rectifier 64, or between the rectifier 64 and the AC power supply 30. In the example shown in Figure 1, the surge protection circuit 61 is provided between the rectifier 64 and the AC power supply 30.

[0026] The hybrid device 60 also includes a relay 65. The relay 65 is located in the AC line 50 connecting the hybrid device 60 and the AC power supply 30, and enables switching between connecting and disconnecting the puncture prevention circuit 61 and the rectifier 64 to the AC power supply 30. When the relay 65 is closed, the puncture prevention circuit 61 and the rectifier 64 are connected to the AC power supply 30, and when the relay 65 is open, the connection between the puncture prevention circuit 61 and the rectifier 64 to the AC power supply 30 is disconnected.

[0027] The hybrid device 60 functions as a DC device capable of operating by receiving DC power from the DC bus line 51 or DC power from the rectifier 64. The hybrid device 60 is not particularly limited and may be, for example, a refrigeration device. Examples of refrigeration devices include air conditioners such as cooling-only units, heating-only units, and air conditioners that switch between cooling and heating. Examples of refrigeration devices include water heaters and chiller units. Furthermore, examples of refrigeration devices include cooling devices that cool the air inside refrigerators, freezers, display cases, containers, etc.

[0028] Power system 1 charges the smoothing capacitor 13 via the interruption prevention circuit 61 and then operates the hybrid equipment 60 when the voltage across the smoothing capacitor 13 is below a predetermined value. The interruption prevention circuit 61 may also charge the smoothing capacitor 13 based on an operation command to the hybrid equipment 60. In this case, when power system 1 receives an operation command to the hybrid equipment 60, it charges the smoothing capacitor 13 via the interruption prevention circuit 61 and then operates the hybrid equipment 60. Alternatively, when power system 1 receives an operation command to the hybrid equipment 60, it may charge the smoothing capacitor 13 via the interruption prevention circuit 61 and then connect the power conditioner 10 to the grid.

[0029] Furthermore, the hybrid equipment 60 may be provided with a detection means for detecting the voltage of the DC bus line 51. In this case, when the power system 1 receives an operation command for the hybrid equipment 60, if the detected voltage is less than a predetermined value, it charges the smoothing capacitor 13 via the surge prevention circuit 61 and then causes the hybrid equipment 60 to operate. On the other hand, if the detected voltage is equal to or greater than the predetermined value, the power system 1 causes the hybrid equipment 60 to operate without charging the smoothing capacitor 13.

[0030] The grid-connection relay 14 is a relay installed in the AC line 50 that connects the power conditioner 10 and the AC power supply 30. The grid-connection relay 14 enables switching between connecting and disconnecting the grid-connection inverter 12 of the power conditioner 10 and the AC power supply 30. When the grid-connection relay 14 is closed, the grid-connection inverter 12 and the AC power supply 30 are connected. Conversely, when the grid-connection relay 14 is open, the connection between the grid-connection inverter 12 and the AC power supply 30 is disconnected.

[0031] When the grid-connected relay 14 is closed, the grid-connected inverter 12 converts AC power from the AC power source 30 into DC power and supplies it to the DC bus line 51. Conversely, when the grid-connected relay 14 is open, DC power from the solar panels 40 is supplied to the DC bus line 51 via the DC / DC converter 11.

[0032] The process from the initial state of power system 1 to the charging of the smoothing capacitor 13 of power conditioner 10 is as follows: In the initial state of power system 1, the solar panels 40 are not generating electricity. Also, the smoothing capacitor 13 of the power conditioner 10 is not charged. Furthermore, the grid connection relay 14 of the power conditioner 10 is open. Also, the relay 65 of the hybrid equipment 60 is open. Therefore, the connection between the hybrid equipment 60 and the AC power supply 30 is disconnected.

[0033] From this initial state, the smoothing capacitor 13 of the power conditioner 10 is charged through a process such as the following. First, an operation command is sent to the hybrid device 60. An operation command is, for example, an operation by the user pressing the start button. Next, the relay 65 of the hybrid device 60 closes. This connects the hybrid device 60 to the AC power supply 30, and an AC voltage is applied to the hybrid device 60. Then, a current flows through the interruption prevention circuit 61 of the hybrid device 60 to charge the smoothing capacitor 13, and DC power is supplied to the smoothing capacitor 13 via the rectifier 64, causing it to charge.

[0034] Here, the hybrid device 60 measures the voltage across the smoothing capacitor 63, and if the voltage across the smoothing capacitor 63 is equal to or greater than a predetermined voltage value when an operation command is received for the hybrid device 60, the step of charging the smoothing capacitor 13 may be omitted. In this case, for example, if the voltage of the AC power supply 30 is 200V, the step of charging the smoothing capacitor 13 may be omitted if the voltage across the smoothing capacitor 63 (the line voltage of the DC bus line 51) is 282V or higher.

[0035] <Second Embodiment> [Overall structure] Figure 2 shows an example of the overall configuration of the power system 2 to which the second embodiment is applied. The configuration of power system 2 shown in Figure 2 is basically the same as that of power system 1 in Figure 1, to which the first embodiment is applied. However, the configuration of power system 2 in Figure 2 differs from power system 1 in Figure 1 in that there are two hybrid devices 60 (hybrid devices 60-1 and 60-2) connected to the DC bus line 51 and the AC line 50.

[0036] In power system 2, where hybrid equipment 60-1 and 60-2 are connected to a DC bus line 51 and an AC line 50, it is possible to charge the smoothing capacitor 13 via the shock-prevention circuit 61 provided by the other in response to an operation command received by one.

[0037] Specifically, for example, when an operation command is received for hybrid equipment 60-1, the smoothing capacitor 13 of the power conditioner 10 may be charged via the interruption prevention circuit 61 of hybrid equipment 60-1. Alternatively, for example, when an operation command is received for hybrid equipment 60-1, the smoothing capacitor 13 of the power conditioner 10 may be charged via the interruption prevention circuit 61 of hybrid equipment 60-2. Furthermore, for example, when an operation command is received for hybrid equipment 60-1, the smoothing capacitor 13 of the power conditioner 10 may be charged via the interruption prevention circuit 61 of hybrid equipment 60-1 and the interruption prevention circuit 61 of hybrid equipment 60-2. These three patterns apply when an operation command is received for hybrid equipment 60-1, but the same applies when an operation command is received for hybrid equipment 60-2.

[0038] <Third Embodiment> [Overall structure] Figure 3 shows an example of the overall configuration of the power system 3 to which the third embodiment is applied. The configuration of power system 3 shown in Figure 3 is basically the same as that of power system 1 in Figure 1, to which the first embodiment is applied. However, power system 3 in Figure 3 differs from power system 1 in Figure 1 in that a DC / DC converter 15 is located in the DC bus line 51 connecting the power conditioner 10 and the hybrid equipment 60. The DC / DC converter 15 is provided inside the power conditioner 10.

[0039] The DC / DC converter 15 is a converter that can limit the current flowing through the DC bus line 51 connecting the power conditioner 10 and the hybrid equipment 60. In power system 3, the hybrid equipment 60 may be operated without using the power conditioner 10. In this case, the DC / DC converter 15 interrupts or limits the current flowing through the DC bus line 51. Control of the conduction and non-conductivity of the DC bus line 51 using such a DC / DC converter 15 is achieved by controlling the on / off switches in the boost circuit and buck circuit. As a result, the power used to charge the smoothing capacitor 13 and standby power are reduced. In addition, the operating efficiency of the hybrid equipment 60 is improved.

[0040] In power system 3, when the smoothing capacitor 13 of the power conditioner 10 is charged via the DC / DC converter 15, DC power is supplied to the hybrid equipment 60 via the DC / DC converter 15. This enables the hybrid equipment 60 to operate.

[0041] Here, the method for supplying power to the hybrid device 60 after the smoothing capacitor 13 of the power conditioner 10 has finished charging is not particularly limited. For example, power from the solar panel 40 may be supplied to the hybrid device 60 via the DC / DC converter 15. Alternatively, power from the AC power supply 30 may be supplied to the hybrid device 60 via the DC / DC converter 15. Alternatively, power from the AC power supply 30 may be supplied to the hybrid device 60 without going through the DC / DC converter 15. Furthermore, for example, power may be supplied to the hybrid device 60 using a combination of these methods.

[0042] The process from the initial state of the power system 3 to the charging of the smoothing capacitor 13 of the power conditioner 10 is as follows: In the initial state of power system 3, the solar panels 40 are not generating power. Also, the smoothing capacitor 13 of the power conditioner 10 and the smoothing capacitor 63 of the hybrid equipment 60 are not charged. Furthermore, the grid connection relay 14 of the power conditioner 10 is open. Also, the relay 65 of the hybrid equipment 60 is open. Furthermore, the DC bus line 51 connecting the power conditioner 10 and the hybrid equipment 60 is non-conductive.

[0043] From this initial state, the smoothing capacitor 13 of the power conditioner 10 is charged through a process such as the following. First, an operation command is sent to the hybrid device 60. An operation command is, for example, an operation by the user pressing the start button. This starts the DC / DC converter 15 and makes it conductive, and the power conditioner 10 and the DC bus line 51 become conductive. Next, the relay 65 of the hybrid device 60 closes. This connects the hybrid device 60 to the AC power supply 30, and an AC voltage is applied to the hybrid device 60. Then, a current flows through the interruption prevention circuit 61 of the hybrid device 60 to charge the smoothing capacitor 13, and DC power is supplied to the smoothing capacitor 13 via the rectifier 64, causing it to charge.

[0044] Here, the power conditioner 10 and the hybrid equipment 60 may be enabled to communicate via wired or wireless means, and the hybrid equipment 60 may notify the power conditioner 10 when it receives an operation command. In this case, the power conditioner 10, upon receiving notification that it has received an operation command from the hybrid equipment 60, drives the switching element of the DC / DC converter 15. This causes the DC / DC converter 15 to start up and become conductive.

[0045] <Fourth Embodiment> [Overall structure] Figure 4 shows an example of the overall configuration of the power system 4 to which the fourth embodiment is applied. The configuration of power system 4 shown in Figure 4 is basically the same as power system 3 in Figure 3 to which the third embodiment is applied, with a DC / DC converter 15 located on the DC bus line 51 connecting the power conditioner 10 and the hybrid equipment 60. However, power system 4 shown in Figure 4 differs from power system 3 in that there are two hybrid equipment 60 (hybrid equipment 60-1 and 60-2) connected to the DC bus line 51 and the AC line 50. In power system 4, one DC / DC converter 15 is shared by hybrid equipment 60-1 and 60-2.

[0046] In the power system 4 shown in Figure 4, similar to the power system 3 shown in Figure 3, the DC / DC converter 15 interrupts or limits the current flowing through the DC bus line 51. Therefore, when operating the hybrid equipment 60-1 and 60-2 without using the power conditioner 10, the power used to charge the smoothing capacitor 13 and standby power can be reduced. In addition, the operating efficiency of the hybrid equipment 60-1 and 60-2 is improved.

[0047] In power system 4, when the smoothing capacitor 13 of the power conditioner 10 is charged via the DC / DC converter 15, DC power is supplied to hybrid devices 60-1 and 60-2 via the DC / DC converter 15. The DC power supplied for charging the smoothing capacitor 13 is supplied via two routes: one via hybrid device 60-1 and the DC / DC converter 15, and the other via hybrid device 60-2 and the DC / DC converter 15. Power system 4 may be configured to use either of these two routes interchangeably, or it may be configured to use both routes.

[0048] <Fifth Embodiment> [Overall structure] Figure 5 shows an example of the overall configuration of the power system 5 to which the fifth embodiment is applied. The configuration of the power system 5 shown in Figure 5 is basically the same as the power system 4 in Figure 4 to which the fourth embodiment is applied, with a DC / DC converter 15 located on the DC bus line 51 connecting the power conditioner 10 and the hybrid equipment 60. However, the power system 5 shown in Figure 5 differs in that it has two DC / DC converters 15. In other words, a DC / DC converter 15 for hybrid equipment 60-1 and a DC / DC converter 15 for hybrid equipment 60-2 are located independently.

[0049] In the power system 5 shown in Figure 5, each of the two DC / DC converters 15 is capable of interrupting or limiting the current flowing through the DC bus line 51. Therefore, when operating the hybrid devices 60-1 and 60-2 without using the power conditioner 10, the power used to charge the smoothing capacitor 13 and standby power can be reduced. In addition, the operating efficiency of the hybrid devices 60-1 and 60-2 is improved.

[0050] In power system 5, when the smoothing capacitor 13 of the power conditioner 10 is charged, DC power is supplied to hybrid device 60-1 via the DC / DC converter 15 for hybrid device 60-1. DC power is also supplied to hybrid device 60-2 via the DC / DC converter 15 for hybrid device 60-2.

[0051] In the power system 5, separate control of the DC / DC converter 15 for hybrid device 60-1 and the DC / DC converter 15 for hybrid device 60-2 becomes possible. For example, the DC / DC converter 15 for hybrid device 60-1 can be controlled to interrupt or limit the current flowing through the DC bus line 51, while the DC / DC converter 15 for hybrid device 60-2 can be controlled to charge the smoothing capacitor 13.

[0052] In power system 5, the smoothing capacitor 13 of the power conditioner 10 is charged through a process such as the following. First, an operation command is issued to hybrid device 60-1. An operation command is, for example, an operation by the user pressing the start button. As a result, the DC / DC converter 15 for hybrid device 60-1 is started and becomes conductive, but no operation command has been issued to hybrid device 60-2. Therefore, the DC / DC converter 15 for hybrid device 60-2 is not started and is not conductive.

[0053] As a result, the power conditioner 10 and the DC bus line 51 for hybrid device 60-1, which connects the power conditioner 10 to hybrid device 60-1, become conductive. In contrast, the power conditioner 10 and the DC bus line 51 for hybrid device 60-2, which connects the power conditioner 10 to hybrid device 60-2, remain non-conductive.

[0054] In this case, current flows through the shock-blocking circuit 61 of the hybrid device 60-1 to charge the smoothing capacitor 13, and DC power is supplied to the smoothing capacitor 13 via the rectifier 64, causing it to charge. When the hybrid device 60-2 is not in operation, the DC / DC converter 15 for the hybrid device 60-2 is deactivated. This makes it possible to choose not to charge the smoothing capacitor 63 of the hybrid device 60-2.

[0055] <Sixth Embodiment> [Overall structure] Figure 6 shows an example of the overall configuration of a power system 6 to which the sixth embodiment is applied. The configuration of the power system 6 shown in Figure 6 is basically the same as that of the power system 1 in Figure 1 to which the first embodiment is applied. However, the power system 6 in Figure 6 differs from the power system 1 in Figure 1 in that it has one hybrid device 60 connected to the DC bus line 51 and the AC line 50, and one DC device 70 connected to the DC bus line 51. The DC device 70 comprises a load 77 consisting of a motor, a DC / AC inverter 72 that converts DC power into AC power suitable for driving the load 77, and a smoothing capacitor 73 that contributes to the stable operation of the load 77 and the DC / AC inverter 72 by smoothing voltage fluctuations.

[0056] As shown in Figure 6, unlike the hybrid device 60, the DC device 70 is not connected to the AC line 50 and does not have a surge protection circuit 61, a rectifier 64, or a relay 65. Therefore, only the hybrid device 60 charges the smoothing capacitor 13, and the DC device 70 does not charge the smoothing capacitor 13.

[0057] In the power system 6 shown in Figure 6, when an operation command is received by the hybrid equipment 60, the smoothing capacitor 13 is charged via the stun prevention circuit 61 provided by the hybrid equipment 60. Conversely, when an operation command is received by the DC equipment 70, the hybrid equipment 60 receives this information, and the smoothing capacitor 13 is charged via the stun prevention circuit 61 provided by the hybrid equipment 60.

[0058] Specifically, the hybrid device 60 and the DC device 70 are enabled to communicate via wired or wireless means, and the DC device 70 notifies the hybrid device 60 when an operation command has been received by the DC device 70. Upon receiving notification that an operation command has been received by the DC device 70, the hybrid device 60 closes the relay 65. This connects the hybrid device 60 to the AC power supply 30, and an AC voltage is applied to the hybrid device 60. As a result, a current flows through the hybrid device 60's surge protection circuit 61 to charge the smoothing capacitor 13, and DC power is supplied to the smoothing capacitor 13 via the rectifier 64, causing it to charge.

[0059] <Seventh Embodiment> [Overall structure] Figure 7 shows an example of the overall configuration of a power system 7 to which the seventh embodiment is applied. The configuration of the power system 7 shown in Figure 7 includes a surge prevention circuit unit 80, which is a separate unitized version of the function of preventing inrush current among the functions of the hybrid equipment 60 of the power system 1 shown in Figure 1 to which the first embodiment is applied.

[0060] The inrush current prevention circuit unit 80 includes an inrush current prevention circuit 81 that prevents inrush current and a rectifier 84 that functions as an AC / DC converter that converts AC power from the AC power supply 30 into DC power. The inrush current prevention circuit unit 80 also includes a relay 85 that enables switching between connecting and disconnecting the inrush current prevention circuit 81 and the rectifier 84 to the AC power supply 30. In the configuration of the power system 7, a hybrid device can be configured as a combination of the DC device 70 and the inrush current prevention circuit unit 80 by connecting the DC device 70 and the inrush current prevention circuit unit 80. Such a hybrid device has the same functions as the hybrid device 60 in the above-described embodiment.

[0061] <Other Embodiments> Each configuration described above is not limited to the embodiments and their variations, and can be modified without departing from the spirit of the claims. In other words, it is understood that a variety of changes in form and details are possible without departing from the spirit and scope of the claims. The configurations described above are not the only ones you may use; you may also omit some of the components in each configuration described above, or add other functions to each configuration described above. Furthermore, although multiple embodiments have been described above, it is also possible to swap the configurations included in one embodiment with those included in other embodiments, or to add the configurations included in one embodiment to other embodiments.

[0062] For example, in the above-described embodiment, the power conditioner 10 is configured to include a DC / DC converter 11, but the DC / DC converter 11 is not an essential component.

[0063] Furthermore, while the fourth embodiment described above involves a configuration in which two hybrid devices 60 (hybrid devices 60-1 and 60-2) are connected to one DC / DC converter 15, the embodiment is not limited to this. For example, a configuration in which multiple hybrid devices 60 and DC devices are connected to one DC / DC converter 15 is also possible.

[0064] Furthermore, while the fifth embodiment described above involves two hybrid devices 60 (hybrid devices 60-1 and 60-2) being connected to two DC / DC converters 15, the embodiment is not limited to this configuration. For example, a configuration in which hybrid devices 60 or DC devices are individually connected to each of the multiple DC / DC converters 15 is also possible.

[0065] Each of the embodiments described above can be understood as follows. In other words, the power system 1 of this disclosure that achieves the above objectives comprises a grid-connected inverter 12, which is an inverter configured to mutually convert AC power from an AC power source 30 and DC power from a DC bus line 51; a power conditioner 10, which is a power converter equipped with a smoothing capacitor 13 connected to the DC bus line 51; an AC / DC converter (rectifier 64 or rectifier 84) that converts AC power from an AC power source 30 to DC power; a surge protection circuit (surge protection circuit 61 or surge protection circuit 81) provided between the DC bus line 51 and the AC / DC converter, or between the AC / DC converter and the AC power source 30; and a DC device (hybrid device 60 or DC device 70) that can operate by receiving DC power from the DC bus line 51 or DC power from the AC / DC converter, wherein if the voltage across the smoothing capacitor 13 is less than a predetermined value, the smoothing capacitor 13 is charged via the surge protection circuit before the DC device is put into operation. In this case, instead of providing a function to prevent inrush current in the power conditioner 10, the inrush current prevention function built into the equipment connected to the DC bus line 51 of the power conditioner 10 can be utilized. This allows for suppression of inrush current while keeping the cost and size of the power conditioner 10 under control, compared to the case where the power conditioner 10 is equipped with an inrush current prevention function.

[0066] Here, the DC equipment, the AC / DC converter, and the shock-blocking circuit may constitute a hybrid device 60, which is an electrical device capable of operating by receiving DC power and AC power. In this case, power can be supplied to the hybrid equipment 60, which is capable of operating by receiving both DC and AC power.

[0067] Furthermore, two or more hybrid devices 60 are connected to the DC bus line 51, and when an operation command is received for the first hybrid device (hybrid device 60-1) among the two or more hybrid devices 60, the smoothing capacitor 13 may be charged via the interruption prevention circuit provided in the second hybrid device (hybrid device 60-2). In this case, reliability can be improved because it becomes possible to select the appropriate circuit from two or more impact prevention circuits.

[0068] Furthermore, the crash prevention circuit may charge the smoothing capacitor 13 based on the operation command to the DC equipment. In this case, it becomes possible to control charging according to the driving command.

[0069] Alternatively, when an operation command is received for a DC device, the smoothing capacitor 13 may be charged via the interruption prevention circuit before the DC device is put into operation. In this case, it becomes possible to control the operation in accordance with the operation command.

[0070] Furthermore, the DC equipment may be further equipped with a detection means for detecting the voltage of the DC bus line 51. When an operation command is received for the DC equipment, if the voltage detected by the detection means is less than a predetermined value, the smoothing capacitor 13 may be charged via a surge protection circuit before the DC equipment is allowed to operate. In this case, control becomes possible according to the detected voltage value of the DC bus line 51.

[0071] Furthermore, the hybrid device 60 is further equipped with a detection means for detecting the voltage of the DC bus line 51. When an operation command is received for the DC device, if the voltage detected by the detection means is greater than or equal to a predetermined value, the hybrid device 60 may be made to operate without charging the smoothing capacitor 13. In this case, control becomes possible according to the detected voltage value of the DC bus line 51.

[0072] Alternatively, when an operation command is received for a DC device, the power conditioner 10 may be connected to the grid after the smoothing capacitor 13 has been charged via the interruption prevention circuit.

[0073] Furthermore, AC / DC converters and DC equipment are connected to the DC bus line 51, and the number of AC / DC converters may be less than the number of DC equipment. In this case, in addition to the hybrid equipment 60 that can receive both DC and AC power, it is possible to accommodate cases where electrical equipment that can receive only DC power is connected.

[0074] Furthermore, a DC / DC converter 15 may be provided in the DC bus line 51 that connects the power conditioner 10 to the DC equipment. In this case, the current flowing through the DC bus line 51 connecting the power conditioner 10 and the DC equipment can be limited. As a result, when operating only the DC equipment without using the power conditioner 10, the power required to charge the power conditioner 10 and the standby power can be reduced by limiting the current flowing through the DC bus line 51.

[0075] Furthermore, the system may include a DC / DC converter 11 configured to convert between the DC power of the solar panel 40, which is a DC power source, and the DC power of the DC bus line 51. In this case, the DC power supplied from the solar panel 40 can be boosted or stepped down as needed and supplied to the DC bus line 51.

[0076] Furthermore, the refrigeration system of this disclosure that achieves the above objectives is a refrigeration system having a refrigeration device as a DC device. In this case, instead of providing a function to prevent inrush current in the power conditioner 10 that supplies DC power to the refrigeration system, the function to prevent inrush current built into the refrigeration system connected to the DC bus line 51 of the power conditioner 10 can be utilized. This allows for suppression of inrush current while keeping the cost and size of the power conditioner 10 down compared to the case where the power conditioner 10 is equipped with a function to prevent inrush current. [Explanation of Symbols]

[0077] 1,2,3,4,5,6,7…Power systems, 10…Power conditioners, 11,15…DC / DC converters, 12…Grid-connected inverters, 13…Smoothing capacitors, 14…Grid-connected relays, 30…AC power supplies, 40…Solar panels, 50…AC lines, 51…DC bus lines, 60…Hybrid equipment, 61…Sudden impact protection circuits, 62,72…DC / AC inverters, 63,73…Smoothing capacitors, 64,84…Rectifiers, 65,85…Relays, 67,77…Loads, 70…DC equipment

Claims

1. A power converter comprising an inverter configured to mutually convert AC power from an AC power source and DC power from a DC bus line, and a smoothing capacitor connected to the DC bus line, An AC / DC converter that converts AC power from the aforementioned AC power source into DC power, An inrush current prevention circuit provided between the DC bus line and the AC / DC converter, or between the AC / DC converter and the AC power supply, A DC device capable of operating by receiving DC power from the DC bus line or DC power from the AC / DC converter, It has, If the voltage across the smoothing capacitor is less than a predetermined value, the DC device is operated after the smoothing capacitor is charged via the inrush current prevention circuit. Power system.

2. The DC equipment, the AC / DC converter, and the inrush current prevention circuit constitute an electrical device capable of operating by receiving DC power and AC power. The power system according to claim 1.

3. Two or more electrical devices are connected to the DC bus line, and when an operation command is received for the first electrical device, the smoothing capacitor is charged via the inrush current prevention circuit provided in the second electrical device. The power system according to claim 2.

4. The inrush current prevention circuit charges the smoothing capacitor based on the operation command to the DC equipment. The power system according to claim 1.

5. When an operation command is received for the DC equipment, the smoothing capacitor is charged via the inrush current prevention circuit, and then the DC equipment is made to operate. The power system according to claim 1.

6. The DC device further comprises detection means for detecting the voltage of the DC bus line, When an operation command is received for the DC equipment, if the voltage detected by the detection means is less than a predetermined value, the smoothing capacitor is charged via the inrush current prevention circuit, and then the DC equipment is made to operate. The power system according to claim 1.

7. The DC device further comprises detection means for detecting the voltage of the DC bus line, When an operation command is received for the DC equipment, if the voltage detected by the detection means is greater than or equal to a predetermined value, the electrical equipment is made to operate without charging the smoothing capacitor. The power system according to claim 2.

8. When an operation command is received for the DC equipment, the power converter is connected to the grid after the smoothing capacitor is charged via the inrush current prevention circuit. The power system according to claim 1.

9. The AC / DC converters and the DC equipment are connected to the DC bus line, and the number of AC / DC converters is less than the number of DC equipment. The power system according to claim 1.

10. The DC bus line connecting the power converter and the DC equipment has a DC / DC converter. The power system according to claim 1.

11. It has a DC / DC converter configured to convert between the DC power of a DC power supply and the DC power of the DC bus line. The power system according to claim 1.

12. A refrigeration device having the DC equipment described in claim 1, Refrigeration system.

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