Power source system

Abstract

A power source system (10) comprises a direct current device (20), a storage cell (30), and a power conversion device (40). The power conversion device (40) comprises an inverter (41) configured by including an IGBT (411S), which is a switching element. The inverter (41) provides a direct current pathway linking the direct current device (20) and the storage cell (30). When an abnormality such as short circuit has occurred, turning off the IGBT (411S) constituting the inverter (41) makes it possible to quickly sever the direct current pathway and electrically disconnect the direct current device (20) and the storage cell (30). By using the inverter (41) as the direct current pathway / relay, it is possible to provide a power source system (10) that can quickly sever the pathway when an abnormality occurs and that is cheap to build.

Description

Power System CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Patent Application No. 2023-188969 filed in Japan on November 3, 2023, and the contents of the original application are incorporated by reference in their entirety.

[0002] TECHNICAL FIELD The disclosure herein relates to power supply systems.

[0003] Patent Document 1 discloses a power supply system, the contents of which are incorporated by reference in this specification as explanations of the technical elements.

[0004] Japanese Patent Application Laid-Open No. 2022-139804

[0005] From the perspective of circular economy, attempts have been made to repurpose the inverter. However, as shown in Patent Document 1, the use is limited. In Patent Document 1, an in-vehicle inverter is used as an inverter for grid connection.

[0006] Furthermore, in a power supply system including a DC device and a storage battery, when an abnormality such as a short circuit occurs, it is necessary to quickly cut off the path connecting the DC device and the storage battery. In the above-mentioned respects and other respects not mentioned, further improvements in power supply systems are required.

[0007] One of the disclosed objects is to provide a power supply system that can quickly shut off a path when an abnormality occurs and that can be constructed inexpensively.

[0008] One aspect of the disclosed power supply system comprises a DC device, a power conversion device including an inverter configured with switching elements, and a storage battery, wherein the inverter provides a DC path connecting the DC device and the storage battery.

[0009] In the disclosed power supply system, the inverter provides a DC path, and a DC circuit is formed that includes a DC device, the inverter, and a storage battery. When an abnormality such as a short circuit occurs, the DC path is quickly interrupted by turning off a switching element that constitutes the inverter, and the DC device and the storage battery are electrically disconnected. The inverter not only provides the DC path but also functions as a relay. In this way, by using the inverter as a DC path and a relay, it is possible to provide a power supply system that can quickly interrupt the path when an abnormality occurs and can be constructed inexpensively.

[0010] The various aspects disclosed in this specification employ different technical means to achieve their respective objectives. The claims and the reference symbols in parentheses in this section are intended to exemplify the correspondence with the embodiments described below and are not intended to limit the technical scope. The objectives, features, and advantages disclosed in this specification will become more apparent by referring to the following detailed description and the accompanying drawings.

[0011] Fig. 1 is a diagram showing a power supply system according to a first embodiment; Fig. 2 is a diagram showing a DC path; Fig. 3 is a diagram showing a power supply system according to a second embodiment; Fig. 4 is a diagram showing a power supply system according to a third embodiment; Fig. 5 is a diagram showing a modified example; Fig. 6 is a diagram showing a power supply system according to a fourth embodiment; Fig. 7 is a diagram showing a modified example.

[0012] Hereinafter, several embodiments will be described with reference to the drawings. Note that in each embodiment, corresponding components are designated by the same reference numerals, and redundant description may be omitted. When only a portion of the configuration is described in each embodiment, the configuration of another embodiment previously described may be applied to the remaining portion of the configuration. Furthermore, in addition to the combinations of configurations explicitly stated in the description of each embodiment, configurations of several embodiments may be partially combined together even if not explicitly stated, provided that there is no particular problem with the combination.

[0013] First Embodiment First, a power supply system will be described with reference to FIG.

[0014] <Power Supply System> Fig. 1 shows a power supply system 10. The power supply system 10 includes a DC device 20, a storage battery 30, a power conversion device 40, and a control device 50.

[0015] The DC device 20 may be a DC power generation device or a DC system (direct current power system). Examples of DC power generation devices include physical batteries such as solar cells and fuel cells. The DC device 20 may include a conductive member for transmitting power, such as a bus bar. The DC device 20 has a positive terminal 21P and a negative terminal 21N.

[0016] The storage battery 30 is a secondary battery that uses a chemical reaction. The storage battery 30 is chargeable and dischargeable. Examples of the storage battery 30 include a lead battery, a sodium-sulfur battery, a nickel-metal hydride battery, and a lithium-ion battery. The storage battery 30 has a positive terminal 31P and a negative terminal 31N.

[0017] The power conversion device 40 includes at least an inverter 41. The power conversion device 40 is converted from a mobile object. Examples of mobile objects include vehicles such as BEVs, HEVs, PHEVs, and FCEVs, aircraft such as eVTOLs, eSTOLs, and drones, ships, construction machinery, and agricultural machinery. As an example, the power conversion device 40 of this embodiment is converted from a vehicle. BEV is an abbreviation for Battery Electric Vehicle. HEV is an abbreviation for Hybrid Electric Vehicle. PHEV is an abbreviation for Plug-in Hybrid Electric Vehicle. FCEV is an abbreviation for Fuel Cell Electric Vehicle. eVTOL is an abbreviation for electronic Vertical Take-Off and Landing aircraft. eSTOL is an abbreviation for electronic Short distance Take-Off and Landing aircraft.

[0018] The power conversion device 40 includes a P line 401, an N line 402, and a three-phase line 403. The P line 401 is a high-potential power line. The N line 402 is a low-potential power line. The three-phase line 403 is connected to the connection points of the corresponding upper and lower arm circuits 411. The three-phase line 403 is sometimes referred to as a three-phase power line. At least a portion of each of the P line 401, the N line 402, and the three-phase line 403 is made of a conductive member such as a bus bar.

[0019] The inverter 41 is configured to include upper and lower arm circuits 411 for three phases. The upper and lower arm circuits 411 are sometimes referred to as legs. The upper and lower arm circuits 411 are connected to a P line 401 and an N line 402. The upper and lower arm circuits 411 each include an upper arm 411H and a lower arm 411L. The upper arm 411H and the lower arm 411L are connected in series between the P line 401 and the N line 402, with the upper arm 411H on the P line 401 side. The connection point between the upper arm 411H and the lower arm 411L is connected to the corresponding three-phase line 403. The inverter 41 has six arms.

[0020] As an example, the elements constituting each arm in this embodiment include an IGBT 411S, which is a switching element, and a freewheeling diode 411D. IGBT is an abbreviation for Insulated Gate Bipolar Transistor. In this embodiment, n-channel IGBTs 411S are used. The diodes 411D are connected in anti-parallel to the corresponding IGBTs 411S. In the upper arm 411H, the collectors of the IGBTs 411S are connected to the P line 401. In the lower arm 411L, the emitters of the IGBTs 411S are connected to the N line 402. The emitters of the IGBTs 411S in the upper arm 411H and the collectors of the IGBTs 411S in the lower arm 411L are connected to each other. The anode of the diode 411D is connected to the emitter of the corresponding IGBT 411S, and the cathode is connected to the collector.

[0021] The switching element is not limited to an IGBT. For example, a MOSFET may be used. MOSFET is an abbreviation for Metal Oxide Semiconductor Field Effect Transistor. In the case of a MOSFET, the diode connected in antiparallel may be a parasitic diode or an external diode.

[0022] The power conversion device 40 has a plurality of terminals. The terminals include terminals 401T, 402T, and 403T. Terminal 401T is a terminal portion provided on the P line 401. Terminal 402T is a terminal portion provided on the N line 402. Terminal 403T is a terminal portion provided individually on the three-phase line 403. Terminal 403T corresponds to the three-phase terminals of the inverter. The inverter 41 has terminals 403T for three phases. Terminal 403T is provided for each phase and may be referred to as a phase terminal or the like.

[0023] At least one of the terminals 403T is electrically connected to the positive terminal 21P of the DC device 20 or the positive terminal 31P of the storage battery 30. In this embodiment, as an example, the terminals 403T for three phases are electrically connected to the positive terminal 21P of the common (single) DC device 20. The negative terminal 21N of the DC device 20 is electrically connected to the terminal 402T. The positive terminal 31P of the storage battery 30 is electrically connected to the terminal 401T, and the negative terminal 31N is electrically connected to the terminal 402T.

[0024] Alternatively, the terminal 403T may be electrically connected to the positive terminal 31P of the storage battery 30. In this case, the negative terminal 31N of the storage battery 30 is electrically connected to the terminal 402T. The positive terminal 21P of the DC device 20 is electrically connected to the terminal 401T, and the negative terminal 21N is electrically connected to the terminal 402T.

[0025] The inverter 41, i.e., the multi-phase upper and lower arm circuits 411, functions as a DC-AC conversion circuit when mounted on the vehicle before conversion, and performs power conversion between a DC power source and a rotating electric machine. The terminal 403T is electrically connected to the stator winding of the corresponding phase of the rotating electric machine. The three-phase line 403 functions as an output line for the rotating electric machine, and the terminal 403T functions as an output terminal. In the power supply system 10 after conversion, the inverter 41 functions as a DC path connecting the DC device 20 and the storage battery 30. It also functions as a relay (eFuse). The terminal 403T functions as a terminal for DC connection.

[0026] Power conversion device 40 further includes a current sensor 42, a smoothing capacitor 43, and a discharge resistor 44. Current sensor 42 individually detects the current flowing through each of three-phase lines 403. Current sensor 42 is fixed, for example, to a bus bar that constitutes three-phase line 403. When mounted on a vehicle, current sensor 42 detects the phase current flowing through the stator winding of each phase.

[0027] The smoothing capacitor 43 smoothes the voltage (DC voltage) between the P line 401 and the N line 402. The positive electrode of the smoothing capacitor 43 is connected to the P line 401, and the negative electrode is connected to the N line 402. The smoothing capacitor 43 is connected in parallel to the upper and lower arm circuits 411 of the inverter 41. As an example, the smoothing capacitor 43 in this embodiment is provided between the upper and lower arm circuits 411 and the storage battery 30. The positive electrode of the smoothing capacitor 43 is electrically connected to the positive electrode (positive terminal 31P) of the storage battery 30, and the negative electrode is electrically connected to the negative electrode (negative terminal 31N) of the storage battery 30.

[0028] The discharge resistor 44 discharges the charge accumulated in the smoothing capacitor 43, for example, to reduce the voltage between the terminals of the smoothing capacitor 43 to a predetermined voltage. One end of the discharge resistor 44 is connected to the P line 401, and the other end is connected to the N line 402. The discharge resistor 44 is connected in parallel to the smoothing capacitor 43. For example, when the supply of power from the DC device 20 is cut off, the discharge resistor 44 forcibly (rapidly) discharges the charge accumulated in the smoothing capacitor 43. The discharge resistor 44 discharges the charge and consumes it as heat. As an example, the discharge resistor 44 in this embodiment is provided between the upper and lower arm circuits 411 and the storage battery 30.

[0029] The control device 50 controls the driving of the switching elements that constitute the power conversion device 40. The control device 50 controls the driving of at least the switching elements that constitute the inverter 41, for example, the IGBT 411S. The control device may include an arithmetic processing circuit including a processor, memory, storage, etc. The processor accesses the memory to execute various processes to realize each function. The memory is, for example, RAM. RAM is an abbreviation for Random Access Memory. The storage includes a non-volatile storage medium such as a flash memory. The storage stores a control program executed by the processor.

[0030] The control device 50 controls the inverter 41 to function as a DC path connecting the DC device 20 and the storage battery 30, and as a relay (eFuse). The control device 50 may be an element of the repurposed power conversion device 40. The control device 50 may store, for example, a control program for a mobile body and a program for the repurposed power supply system. For example, the program for the power supply system may be stored in advance when mounted on the vehicle. Upon repurposing, the control program for the power supply system may be written to the control device 50. Upon repurposing, the control program may be rewritten for the power supply system. The control device 50 may be provided separately from the power conversion device 40. In other words, the control device 50 may be configured as an unrepurposed device.

[0031] <DC Path and Relay> Fig. 2 shows the DC path provided by the inverter. The control device 50 controls the driving of the switching elements constituting the inverter 41, thereby causing the inverter 41 to function as a DC path and ultimately as a relay. The control device 50 turns on the switching element of the upper arm 411H of the upper and lower arm circuit 411 corresponding to the terminal 403T connected to the positive terminal 21P or the positive terminal 31P, thereby electrically connecting the positive terminal 21P of the DC device 20 and the positive terminal 31P of the storage battery 30 via the turned-on switching element. The control device 50 turns off the other switching elements.

[0032] In this embodiment, as an example, the IGBTs 411S of the upper arms 411H of all three phases are always turned on, and the IGBTs 411S of the lower arms 411L are always turned off. This electrically connects the P line 401 to the terminal 403T, and electrically separates the N line 402 from the terminal 403T. As shown by the thick solid lines in FIG. 2 , the power conversion device 40 including the inverter 41 provides a positive-side (high-potential) DC path including the three-phase terminals 403T, the IGBTs 411S of the upper arms 411H of the three phases, the P line 401, and the terminal 401T. The terminal 402T provides a negative-side (low-potential) DC path electrically connecting the negative terminal 21N of the DC device 20 and the negative terminal 31N of the storage battery 30. The inverter 41 functions as a DC wiring for transmitting DC power between the DC device 20 and the storage battery 30.

[0033] When an abnormality such as a leakage current, a short circuit, or a ground fault occurs, the control device 50 turns off the IGBT 411S of the upper arm 411H to electrically disconnect the DC device 20 from the storage battery 30. The inverter 41 functions as a relay (eFuse). When an abnormality detection condition is satisfied, for example, when a value detected by the current sensor 42 exceeds a predetermined threshold, the control device 50 turns off the IGBT 411S of the upper arm 411H.

[0034] Summary of First Embodiment According to this embodiment, the inverter 41 provides a DC path, and a DC circuit is formed including the DC device 20, the inverter 41, and the storage battery 30. When an abnormality such as a short circuit occurs, the DC path is quickly interrupted by turning off the switching elements constituting the inverter 41, and the DC device 20 and the storage battery 30 can be electrically disconnected. The inverter 41 not only provides the DC path but also functions as a relay. In this way, because the inverter 41 is used as the DC path and a relay, it is possible to inexpensively construct a power supply system 10 that can quickly interrupt the path when an abnormality occurs.

[0035] At least one of the three-phase terminals 403T of the inverter 41 may be electrically connected to a positive electrode of one of the DC device 20 and the storage battery 30 to be connected. The positive electrode is the positive electrode terminal 21P or the positive electrode terminal 31P. By turning on the switching element constituting the upper arm 411H, the inverter 41 functions as a DC path connecting the DC device 20 and the storage battery 30. By using the terminal 403T as a DC connection terminal, it is possible to construct a power supply system 10 that can quickly shut off the path when an abnormality occurs at a lower cost without adding any additional DC connection terminals or devices.

[0036] The power conversion device 40 including the inverter 41 may be one that has been diverted from a mobile object such as a vehicle. Because the power conversion device 40 that was used in the mobile object is diverted, the power supply system 10 can be constructed inexpensively.

[0037] The power conversion device 40 may include a current sensor 42 provided corresponding to the terminal 403T. Current measurement is possible without providing a separate current sensor. In other words, the current measurement function of the DC device 20 or the storage battery 30 can be realized without increasing costs. Furthermore, a configuration that detects abnormalities such as short circuits and quickly shuts off power when an abnormality occurs can be inexpensively constructed. The storage battery 30 in this embodiment employs a commonly known rechargeable secondary battery, but the present invention is not limited to this and also includes devices that produce and store hydrogen. In other words, any device that flows direct current and stores it as energy is included in the storage battery of the present invention.

[0038] Second Embodiment This embodiment is a modification of the preceding embodiment as a basic form, and the description of the preceding embodiment can be used. In the preceding embodiment, the negative pole of the connection target is connected to the N-line terminal. Instead of this, a configuration may be adopted in which the positive pole of the connection target is connected to some of the three-phase terminals of the inverter, and the negative pole of the connection target is connected to the other part.

[0039] FIG. 3 shows a power supply system according to this embodiment. FIG. 3 shows a DC path provided by a power conversion device including an inverter. As an example, in this embodiment as well, the positive terminal 31P of the storage battery 30 is electrically connected to a terminal 401T, and the negative terminal 31N is electrically connected to a terminal 402T. The positive terminal 21P of the DC device 20 is electrically connected to a part of the three-phase terminals 403T. The negative terminal 21N of the DC device 20 is electrically connected to a terminal 403T other than the terminal 403T to which the positive terminal 21P is connected. In the example shown in FIG. 3, two terminals 403T and the positive terminal 21P are electrically connected, and the remaining terminal 403T and the negative terminal 21N are electrically connected.

[0040] The control device 50 turns on the switching element of the upper arm 411H of the upper and lower arm circuit 411 corresponding to the terminal 403T connected to the positive terminal 21P, thereby electrically connecting the positive terminal 21P of the DC device 20 and the positive terminal 31P of the storage battery 30 through the turned-on switching element. The control device 50 turns on the switching element of the lower arm 411L of the upper and lower arm circuit 411 corresponding to the terminal 403T connected to the negative terminal 21N, thereby electrically connecting the negative terminal 21N of the DC device 20 and the negative terminal 31N of the storage battery 30 through the turned-on switching element.

[0041] As shown by the thick solid lines in Fig. 3 , the power conversion device 40 including the inverter 41 provides a DC path on the positive side (high potential side) including two-phase terminals 403T, IGBTs 411S of two-phase upper arms 411H, P line 401, and terminal 401T. The inverter 41 provides a DC path on the negative side (low potential side) including one-phase terminal 403T, IGBTs 411S of one-phase lower arms 411L, N line 402, and terminal 402T. The inverter 41 functions as DC wiring for transmitting DC power between the DC device 20 and the storage battery 30. The other configurations are similar to those of the power supply system 10 described in the preceding embodiment.

[0042] As illustrated in this embodiment, a terminal 403T other than the terminal 403T connected to the positive terminal 21P may be electrically connected to the negative terminal 21N. In other words, some of the multiple terminals 403T may be electrically connected to the positive terminal 21P, and other of the multiple terminals 403T may be electrically connected to the negative terminal 21N.

[0043] This eliminates the need for a mechanism for branching terminal 402T, such as a J / B. Since there is no need to add a J / B, the power supply system 10 can be constructed at even lower cost, allowing for quick disconnection of the path when an abnormality occurs. J / B is an abbreviation for junction box. Furthermore, since terminal 403T is connected to the negative terminal 21N, the path can be quickly disconnected when a ground fault occurs. Not only the path on the positive side, but also the path on the negative side can be disconnected when an abnormality occurs.

[0044] The number of terminals 403T electrically connected to the positive terminal 21P is not limited to two. The number of terminals 403T electrically connected to the negative terminal 21N is not limited to one. For example, one terminal 403T may be connected to the positive terminal 21P, and two terminals 403T may be connected to the negative terminal 21N. One terminal 403T may be connected to the positive terminal 21P, and one terminal 403T may be connected to the negative terminal 21N. In other words, a configuration may be adopted in which some of the terminals 403T are not electrically connected to the DC device 20.

[0045] As described in the preceding embodiment, the terminal 403T may be connected to the storage battery 30. In this case, some of the multiple terminals 403T are electrically connected to the positive terminal 31P, and other of the multiple terminals 403T are electrically connected to the negative terminal 31N.

[0046] Third Embodiment This embodiment is a modification based on the preceding embodiment, and the description of the preceding embodiment can be used. In the preceding embodiment, an inverter is used as a DC path and a relay. In addition to these functions, a configuration including an inverter may provide a step-up / step-down function.

[0047] FIG. 4 shows a power supply system according to this embodiment. FIG. 4 shows a DC path provided by a power conversion device including an inverter. The thick solid lines in FIG. 4 indicate a state in which the IGBT 411S of the three-phase upper arm 411H is turned on. The power supply system 10 according to this embodiment includes an inductor 45 in addition to the DC device 20, the storage battery 30, the power conversion device 40, and the control device 50. The inductor 45 is disposed between the terminal 403T and the positive terminal of the DC device 20 or the storage battery 30 to be connected (the path). The inductor 45 may also be referred to as a reactor, a coil, or the like. The power conversion device 40 may include the inductor 45.

[0048] In the example shown in Fig. 4, the inductor 45 is a stator winding 451. The inductor 45 includes three phases of stator windings 451. The stator windings 451 may be provided, for example, in a form in which the rotor is removed from a rotating electric machine. The three phases of stator windings 451 are Y-connected. The positive terminal 21P of the DC device 20 is electrically connected to the end of each stator winding 451 on the neutral point side. The terminal 403T is individually connected to the end of each stator winding 451 opposite the neutral point.

[0049] In this way, the stator winding 451 is arranged in a path connecting the DC device 20 and the upper and lower arm circuits 411. The stator winding 451 and the upper and lower arm circuits 411 form a step-up / step-down converter. The stator winding 451 and the inverter 41 form a multi-phase converter, specifically a three-phase converter.

[0050] The power supply system 10 may include a capacitor 46. The capacitor 46 is sometimes referred to as a filter capacitor. The positive electrode of the capacitor 46 is connected to a wiring that connects the stator winding 451 and the positive terminal 21P of the DC device 20. The negative electrode of the capacitor 46 is connected to a wiring that connects the negative terminal 21N of the DC device 20 and a terminal 402T. The power conversion device 40 may include the capacitor 46.

[0051] The control device 50 controls the driving of the IGBT 411S, which is a switching element, so that the output voltage of the above-mentioned step-up / step-down converter, i.e., the voltage across the smoothing capacitor 43, becomes a predetermined voltage. The control device 50 controls the driving of the IGBT 411S so that the inductor 45 and the inverter 41 perform step-up / step-down operation as necessary. The control device 50 may switch the number of phases to be driven depending on the output voltage of the step-up / step-down converter. The other configurations are the same as those of the power supply system 10 described in the preceding embodiment.

[0052] Summary of Third Embodiment As illustrated in this embodiment, the power supply system 10 may include an inductor 45 disposed between the positive terminal 21P of the DC device 20 and the terminal 403T. This allows the inductor 45 and the inverter 41 to function as a step-up / step-down converter. This allows the potential of the P line 401 to be set as desired. In other words, the voltage across the smoothing capacitor 43 can be set to any desired voltage. The inverter 41 functions as a converter in addition to being a DC path and a relay.

[0053] A stator winding 451 of a rotating electric machine may be used as the inductor 45. For example, if an eAxle unit, which integrates a rotating electric machine and a power conversion device, is diverted from a mobile body to the power supply system 10, a configuration with a step-up / step-down function can be constructed at low cost.

[0054] As described in the preceding embodiment, the negative electrode terminal 21N may be electrically connected to the terminal 403T. In this case, the positive electrode terminal 21P is electrically connected to a terminal 403T other than the terminal 403T to which the negative electrode terminal 21N is connected via the inductor 45. The terminal 403T may also be connected to the storage battery 30.

[0055] The number of inductors 45 is not limited to the above example. It is sufficient that the inductor 45 is connected to at least one of the terminals 403T. The inductor 45 may be connected to only one of the terminals 403T, and only the upper and lower arm circuits 411 for one phase corresponding to the terminal 403T to which the inductor 45 is connected may be used for the step-up and step-down operation. In other words, the step-up and step-down converter formed by the inductor 45 and the inverter 41 is not limited to being multi-phase.

[0056] 5, an EMC filter core 452 may be used instead of the stator winding 451. By disposing the EMC filter core 452 (iron core) between the positive electrode terminal 21P and the terminal 403T, the core 452 and the inverter 41 can function as a step-up / step-down converter. By repurposing an EMC filter disposed in the power supply line of a mobile object, for example, a configuration with added step-up / step-down functionality can be constructed at low cost.

[0057] Although not shown, when driving the IGBTs 411S of N (N is an integer of 2 or more) upper and lower arm circuits 411, the control device 50 may drive the IGBTs 411S with a phase shift of 360 degrees / N. In this way, the multi-phase upper and lower arm circuits 411, i.e., the inverters 41, may be configured to be interleaved. This suppresses ripple current and allows, for example, the size of the smoothing capacitor 43 to be reduced.

[0058] Fourth Embodiment This embodiment is a modification based on the preceding embodiment, and the description of the preceding embodiment can be used. In the preceding embodiment, the power conversion device includes only one inverter. Instead of this, the power conversion device may include multiple inverters and a buck-boost converter provided separately from the inverters.

[0059] FIG. 6 shows a power supply system according to this embodiment. FIG. 6 shows a DC path provided by a power conversion device including an inverter. The thick solid lines in FIG. 6 indicate a state in which the IGBT 411S of the three-phase upper arm 411H is turned on. The power supply system 10 according to this embodiment includes a DC device 20, a storage battery 30, a power conversion device 40, and a control device 50, similar to the configuration shown in the first embodiment (see FIG. 1 ). In this embodiment, the DC device 20 is a solar cell 201, for example. The power conversion device 40 further includes a step-up / step-down converter 47, an inverter 48, and a capacitor 49 in addition to an inverter 41, a current sensor 42, a smoothing capacitor 43, and a discharge resistor 44. As shown in the previous embodiment, the power conversion device 40 is adapted from a mobile object, such as a vehicle.

[0060] Power conversion device 40 includes, as P lines 401, P line 401H to which inverter 41 is connected, and P line 401L connecting solar cell 201 and step-up / step-down converter 47. The potential of P line 401H is equal to or higher than the potential of P line 401L. P line 401H is sometimes referred to as a VH line, and P line 401L is sometimes referred to as a VL line. Power conversion device 40 includes three-phase lines 403 corresponding to inverter 41, as well as three-phase lines 404 corresponding to inverter 48.

[0061] The power conversion device 40 has a plurality of terminals. The terminals include the terminals 401T, 402T, and 403T described in the preceding embodiment, as well as a terminal 404T. The terminal 404T is a terminal portion individually provided on the three-phase line 404. The terminal 401T is provided on the P line 401L of the P line 401. The terminal 401T is electrically connected to the positive terminal 21P of the solar cell 201. The terminal 402T is electrically connected to the negative terminal 21N of the solar cell 201.

[0062] The upper and lower arm circuits 411 of the inverter 41 are connected to the P line 401H and the N line 402. The terminal 403T is electrically connected to the positive terminal 31P of the storage battery 30. The negative terminal 31N of the storage battery 30 is electrically connected to the terminal 402T. The smoothing capacitor 43 and the discharge resistor 44 are also connected to the P line 401H and the N line 402.

[0063] The buck-boost converter 47 is a DC-DC conversion circuit and includes upper and lower arm circuits 471 and an inductor 472. The configuration of the upper and lower arm circuit 471 is similar to the configuration of the upper and lower arm circuit 411. The number of upper and lower arm circuits 471 and the number of inductors 472 included in the buck-boost converter 47 are not particularly limited. The buck-boost converter 47 may be multi-phase. As an example, the buck-boost converter 47 of this embodiment has a single-phase configuration.

[0064] The upper and lower arm circuit 471 has an upper arm 471H and a lower arm 471L. The upper arm 471H and the lower arm 471L are connected in series between the P line 401H and the N line 402, with the upper arm 471H on the P line 401H side. The elements constituting each arm include an IGBT 471S which is a switching element and a freewheeling diode 471D.

[0065] As described above, the inductor 472 may be referred to as a reactor, a coil, etc. One end of the inductor 472 is connected to the P line 401L. The other end of the inductor 472 is connected to the connection point between the upper arm 471H and the lower arm 471L.

[0066] The inverter 48 has a configuration similar to that of the inverter 41. The inverter 48 functions as a DC-AC conversion circuit in the power supply system 10. The inverter 48 is configured with upper and lower arm circuits 481 for three phases. The upper and lower arm circuits 481 are connected to the P line 401H and the N line 402. The upper and lower arm circuits 481 each have an upper arm 481H and a lower arm 481L. The upper arm 481H and the lower arm 481L are connected in series between the P line 401H and the N line 402, with the upper arm 481H on the P line 401H side. The connection point between the upper arm 481H and the lower arm 481L is connected to the corresponding three-phase line 404. The inverter 48 has six arms. The elements constituting each arm include an IGBT 481S, which is a switching element, and a reflux diode 481D.

[0067] The terminal 404T is electrically connected to the AC device 60. The AC device 60 is, for example, an AC load, an AC system (alternating current power system), or the like. As an example, the AC device 60 in this embodiment is an AC system 601 (alternating current power system). The power supply system 10 forms a solar power generation system. For example, the voltage of DC power output by the solar cell 201 is adjusted by the step-up / step-down converter 47, converted into AC power by the inverter 48, and output to the AC system 601.

[0068] A current sensor 42 is also provided on the three-phase line 404. The current sensor 42 individually detects the current flowing through each of the three-phase lines 404. The current sensor 42 is fixed to a bus bar that constitutes the three-phase line 403, for example.

[0069] Capacitor 49 is connected to P line 401L and N line 402 on the side of terminals 401T and 402T from step-up / step-down converter 47. The positive electrode of capacitor 49 is connected to P line 401L, and the negative electrode is connected to N line 402. Capacitor 49 is sometimes called a filter capacitor.

[0070] The control device 50 controls the driving of the switching elements that constitute the inverter 41, the switching elements that constitute the step-up / step-down converter 47, and the switching elements that constitute the inverter 48. The control device 50 controls the inverter 41 to function as a DC path and a relay. The control device 50 controls the step-up / step-down converter 47 to perform step-up / step-down operation. The control device 50 controls the inverter 48 to perform an operation of converting to AC power. The other configurations are the same as those of the power supply system 10 described in the preceding embodiment.

[0071] Summary of Fourth Embodiment As illustrated in this embodiment, the power conversion device 40 may include an inverter 48 (second inverter) provided separately from the inverter 41 (first inverter). The power conversion device 40 may include a step-up / step-down converter 47 provided between the DC device 20 and the inverter 41. Three-phase terminals 404T of the inverter 48 may be electrically connected to the AC device 60.

[0072] As described in the preceding embodiment, the inverter 41 functions as a DC path and a relay. For example, in a configuration in which the terminal 403T is connected to the storage battery 30, DC power output from the DC device 20 (solar cell 201) is boosted or bucked to a predetermined voltage by the boost / buck converter 47 and supplied to the storage battery 30 through the DC path of the inverter 41. When an abnormality such as a short circuit occurs, the DC path can be quickly interrupted by turning off the switching elements constituting the inverter 41, thereby electrically disconnecting the DC device 20 and the storage battery 30. Because the inverter 41 is used as a DC path and a relay, the power supply system 10 that can quickly interrupt the path when an abnormality occurs can be constructed at low cost.

[0073] Furthermore, since the power conversion device 40 includes the two inverters 41, 48 and the step-up / step-down converter 47, it is possible to inexpensively construct the power supply system 10 that is capable of transmitting and receiving power between the DC device 20, the storage battery 30, and the AC device 60. In this embodiment as well, the power conversion device 40 that has been used in a mobile body such as a vehicle can be repurposed, so the power supply system 10 can be inexpensively constructed.

[0074] The DC device 20 may be a solar cell 201. In this case, the power supply system 10 functions as a solar power generation system. The solar power generation system can be constructed inexpensively. Furthermore, since the inverter 41 is used as a DC path and a relay, the DC path can be quickly cut off in the event of an abnormality such as a short circuit, and the DC device 20 and the storage battery 30 can be electrically disconnected.

[0075] The power conversion device may include a current sensor 42 provided corresponding to the terminal 404T (inverter 48). Current measurement is possible without providing a separate current sensor. In other words, current measurement is possible without increasing costs.

[0076] <Modification> The number of inverters included in the power conversion device 40 is not limited to two. The power conversion device 40 may include one first inverter (inverter 41) and multiple second inverters. Some of the multiple second inverters may be connected to an AC system, and other parts of the second inverters may be connected to AC loads.

[0077] The DC device 20 is not limited to the solar cell 201. As described in the previous embodiment, it may be another DC power generating device such as a fuel cell, or a DC system.

[0078] Although an example has been shown in which the terminals 401T and 402T are connected to the DC device 20 (solar cell 201) and the terminal 403T is connected to the storage battery 30, the present invention is not limited to this. The terminals 401T and 402T may be connected to the storage battery 30, and the terminal 403T may be connected to the DC device 20.

[0079] As shown in the third embodiment, an inductor 45 may be connected to the terminal 403T, allowing the inverter 41 to function as a DC path, a relay, and a step-up / step-down converter. In FIG. 7 , a stator winding 451 is shown as an example of the inductor 45. The terminal 403T is electrically connected to the positive terminal 21P of the solar cell 201 via the stator winding 451. The negative terminal 21N of the solar cell 201 is electrically connected to the terminal 402T. As in the third embodiment, the positive electrode of the capacitor 46 is connected to the wiring connecting the stator winding 451 and the positive terminal 21P of the DC device 20. The negative electrode of the capacitor 46 is connected to the wiring connecting the negative terminal 21N of the DC device 20 and the terminal 402T. The other configurations are the same as those shown in FIGS. 4 and 6 .

[0080] One of the inverter 41 and the step-up / step-down converter 47 is connected to the DC device 20 (solar cell 201), and the other is connected to the storage battery 30. That is, in FIG. 7 , the step-up / step-down converter is connected to both the DC device 20 and the storage battery 30.

[0081] 6 and 7, the potential of P line 401H relative to the potential of N line 402, i.e., the voltage across smoothing capacitor 43, is defined as VH. The potential of P line 401L relative to the potential of N line 402, i.e., the voltage across capacitor 49, is defined as VL1. The potential of the positive electrode of DC device 20 or storage battery 30 connected to terminal 403T relative to the potential of N line 402 is defined as voltage VL2. The voltage of AC device 60 is defined as VAC.

[0082] In the circuit configuration shown in FIG. 6, the following equations 1 and 2 hold true. m is the modulation factor. In sinusoidal PWM control, the modulation factor m is set, for example, within the range of 0 to 0.612. δ1 is the voltage step-up / step-down coefficient. VAC = m × VH = m × VL2 (1) VL1 = δ1 × VH (2) Because voltage VL2 is not stepped up or down (variable), voltage VH is bound by voltage VL2. In other words, voltage VL2 determines the maximum voltage that can be output by voltage VAC. For example, a 200V output requires the connection of a DC device with a DC voltage of 327V or higher.

[0083] On the other hand, in the circuit configuration shown in FIG. 7, the following equations 3, 4, and 5 hold. δ2 is also a voltage step-up / step-down coefficient. f() is a function. VAC=m×VH=m×f(VL1 / δ1, VL2 / δ2) (3) VL1=δ1×VH (4) VL2=δ2×VH (5) Since voltage VL2 is stepped up / down (variable) as shown in equation 5, voltage VH, and therefore voltage VAC, can be set to any value as shown in equation 3.

[0084] The configuration described in the third embodiment can be applied to the configuration in which the inductor 45 is connected to turn the inverter 41 into a step-up / step-down converter. For example, the core 452 of an EMC filter may be used instead of the stator winding 451. The inductor 45 may be connected to at least one of the terminals 403T.

[0085] The configuration described in this embodiment may be combined with the configuration described in the second embodiment. Some of the multiple terminals 403T may be electrically connected to the positive terminal of the connection target (the DC device 20 or the storage battery 30), and another part of the multiple terminals 403T may be electrically connected to the negative terminal of the connection target.

[0086] When diverting the power conversion device 40, the thermal resistance Rth of the switching elements in the upper arm of each inverter may be calculated using the temperature, voltage VH, and detected values ​​of the current sensor 42 of the switching elements constituting the inverter. The temperature of the switching elements may be detected, for example, by a temperature-sensitive diode built into the element. The three-phase terminals of the inverter including the switching element with the highest thermal resistance, i.e., the most degraded, may then be electrically connected to the positive terminals of the DC device 20 or the storage battery 30. That is, the inverter including the switching element with the highest thermal resistance may be used in the DC path, and the inverter with the switching element with the lowest thermal resistance may be used for connection to the AC device 60. Applying healthy phases to AC system interconnections where high loads are expected can extend the product life after diverting.

[0087] (Other Embodiments) The disclosure in this specification and drawings, etc. is not limited to the exemplified embodiments. The disclosure encompasses the exemplified embodiments and modifications thereto by those skilled in the art. For example, the disclosure is not limited to the combinations of parts and / or elements shown in the embodiments. The disclosure can be implemented in various combinations. The disclosure can have additional parts that can be added to the embodiments. The disclosure encompasses the omission of parts and / or elements from the embodiments. The disclosure encompasses the substitution or combination of parts and / or elements between one embodiment and another embodiment. The disclosed technical scope is not limited to the description of the embodiments. Some disclosed technical scopes are defined by the claims, and should be interpreted as including all modifications within the meaning and scope equivalent to the claims.

[0088] The disclosure in the specification, drawings, etc. is not limited by the claims. The disclosure in the specification, drawings, etc. encompasses the technical ideas described in the claims, and extends to more diverse and broader technical ideas than the technical ideas described in the claims. Therefore, various technical ideas can be extracted from the disclosure in the specification, drawings, etc. without being bound by the claims.

[0089] When an element or layer is referred to as being "on," "coupled," "connected," or "coupled," it may be directly coupled, connected, or coupled to another element or layer, and intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly coupled," "directly connected," or "directly coupled" to another element or layer, no intervening elements or layers are present. Other words used to describe relationships between elements should be construed in a similar manner (e.g., "between" vs. "directly between," "adjacent" vs. "directly adjacent," etc.). As used in this specification, the term "and / or" includes any and all combinations of one or more of the associated listed items. That is, a reference to A and / or B means at least one of A and B, and can include A only, B only, or both A and B.

[0090] Spatially relative terms such as "inside," "outside," "back," "below," "low," "top," "top," and the like are used herein to facilitate the description of one element or feature's relationship to other elements or features, as illustrated. Spatially relative terms may be intended to encompass different orientations of the device during use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures were turned over, elements described as "below" or "directly below" other elements or features would then be oriented "above" the other elements or features. Thus, the term "bottom" can encompass both an orientation of top and bottom. The device may also be oriented in other ways (rotated 90 degrees or at other orientations), and the spatially relative descriptors used in this specification would be interpreted accordingly.

[0091] (Disclosure of Technical Ideas) This specification discloses multiple technical ideas described in the following multiple clauses. Some clauses may be described in a multiple dependent form, with the subsequent clause alternatively referring to the preceding clause. Furthermore, some clauses may be described in a multiple dependent form, with the subsequent clause referring to another multiple dependent clause. These multiple dependent clauses define multiple technical ideas.

[0092] <Technical Idea 1> A power supply system comprising: a DC device (20); a power conversion device (40) including an inverter (41) configured with a switching element (411S); and a storage battery (30), wherein the inverter provides a DC path connecting the DC device and the storage battery.

[0093] <Technical Idea 2> The power supply system according to Technical Idea 1, wherein at least one of the three-phase terminals (403T) of the inverter is electrically connected to a positive electrode of a connection target that is one of the DC device and the storage battery.

[0094] <Technical Concept 3> The power supply system according to Technical Concept 2, wherein a terminal of the inverter other than a terminal connected to the positive electrode is electrically connected to the negative electrode of the connection target.

[0095] <Technical Idea 4> The power supply system according to Technical Idea 2 or Technical Idea 3, further comprising an inductor (45) arranged between the positive electrode of the connection target and a terminal of the inverter, wherein the inductor and the inverter are capable of stepping up and down a voltage.

[0096] <Technical Concept 5> The power supply system according to Technical Concept 4, wherein the inductor is a stator winding (451) of a rotating electric machine.

[0097] <Technical Concept 6> The power supply system according to Technical Concept 4, wherein the inductor is a core (452) of an EMC filter.

[0098] <Technical Concept 7> The power supply system according to any one of Technical Concepts 4 to 6, wherein the inverter is driven in an interleaved manner.

[0099] <Technical Idea 8> The power supply system according to any one of Technical Ideas 1 to 7, wherein the inverter is a first inverter, and the power conversion device includes, in addition to the first inverter, a step-up / step-down converter (47) provided between the first inverter and one of the DC device and the storage batteries, and at least one second inverter (48) connected in parallel to the first inverter, and three-phase terminals (404T) of the second inverter are electrically connected to an AC device (60).

[0100] Technical Concept 9: The power supply system according to Technical Concept 8, wherein the DC device is a solar cell (201).

[0101] <Technical Concept 10> The power supply system according to any one of Technical Concepts 1 to 9, wherein the power conversion device is adapted from a mobile body.

[0102] <Technical Concept 11> The power supply system according to any one of Technical Concepts 1 to 10, wherein the power conversion device includes a current sensor (42).

Claims

1. A power supply system comprising: a DC device (20); a power conversion device (40) including an inverter (41) configured with a switching element (411S); and a storage battery (30), wherein the inverter provides a DC path connecting the DC device and the storage battery.

2. The power supply system according to claim 1, wherein at least one of the three-phase terminals (403T) of the inverter is electrically connected to a positive electrode of a connection target which is one of the DC device and the storage battery.

3. The power supply system according to claim 2, wherein a terminal of the inverter other than the terminal connected to the positive electrode is electrically connected to the negative electrode of the connection target.

4. The power supply system according to claim 2, further comprising an inductor (45) disposed between the positive electrode of the connection target and a terminal of the inverter, wherein the inductor and the inverter are capable of stepping up and stepping down a voltage.

5. The power supply system according to claim 4, wherein the inductor is a stator winding (451) of a rotating electrical machine.

6. The power system of claim 4, wherein the inductor is a core (452) of an EMC filter.

7. The power supply system according to any one of claims 4 to 6, wherein the inverter is driven in an interleaved manner.

8. The power supply system according to any one of claims 1 to 4, wherein the inverter is a first inverter, and the power conversion device includes, in addition to the first inverter, a step-up / step-down converter (47) provided between the first inverter and one of the DC device and the storage batteries, and at least one second inverter (48) connected in parallel to the first inverter, and three-phase terminals (404T) of the second inverter are electrically connected to an AC device (60).

9. The power supply system of claim 8, wherein the DC device is a solar cell (201).

10. The power supply system according to any one of claims 1 to 4, wherein the power conversion device is adapted from a mobile body.

11. The power supply system according to any one of claims 1 to 4, wherein the power conversion device includes a current sensor (42).

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