Power supply system including engine generator

Abstract

The present invention is for effectively utilizing an engine generator provided as a backup power supply for a power supply system even when an engine is stopped. According to the present invention, in a power generation mode, a control circuit disconnects a power generator from an engine generator by controlling a switch, and controls a plurality of switch elements to rectify the alternating current with a rectifier circuit. In a converter mode, the control circuit connects the power generator to the engine generator by controlling the switch, accumulates the energy supplied from the power generator in a winding during a boosting period in which the voltage supplied from the power generator is boosted, and controls the plurality of switch elements to release the energy accumulated in the winding during a release period.

Description

[Technical Field]

[0001] The present invention relates to a power supply system including an engine generator. [Background technology]

[0002] One method for achieving the Sustainable Development Goals (SDGs) is the electrification of automobiles. Patent Document 1 proposes an AC charger for charging the battery of a plug-in hybrid vehicle from a commercial AC power source. Patent Document 2 proposes a DC charger for charging the battery of an electric vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-068362 [Patent Document 2] Patent Publication No. 2021-035202 Summary of the Invention [Problem to be solved by the invention]

[0004] To realize a decarbonized society, off-grid systems using renewable energy are necessary. For example, an off-grid system combining solar power generation, wind power generation, and storage batteries could effectively utilize renewable energy. However, the output of solar power generation and wind power generation is affected by weather, and the remaining capacity of storage batteries can decrease, causing output instability. Therefore, when renewable energy cannot be used, an engine generator would be effective as a backup power source. However, engine generators as backup power sources are used extremely rarely, resulting in a low utilization rate. Therefore, an object of the present invention is to effectively utilize an engine generator provided as a backup power source for a power supply system even when the engine is stopped. [Means for solving the problem]

[0005] According to the present invention, for example, 1. A power supply system, comprising: a power generation device that generates electricity using renewable energy; An engine generator, a switch that connects the power generation device and the engine generator; a control circuit for controlling the switch; The engine generator includes: a generator including a winding; an engine that drives the generator; a rectifier circuit connected to the generator and having a plurality of switch elements for rectifying the alternating current generated in the winding; a smoothing circuit that smoothes the pulsating current output from the rectifier circuit, The control circuit In a power generation mode in which the generator of the engine generator is driven by the engine to generate power, the switch is controlled to disconnect the power generation device from the engine generator, and the AC is rectified by the rectifier circuit by controlling the plurality of switch elements; in a converter mode in which the generator of the engine generator does not generate power, controlling the switches to connect the power generation device to the engine generator, and controlling the plurality of switch elements so as to store energy supplied from the power generation device in the winding during a boost period in which the voltage supplied from the power generation device is boosted, and to release the energy stored in the winding to the smoothing circuit during a release period; in the converter mode, the winding, a capacitor of the smoothing circuit, and at least two switch elements among the plurality of switch elements form a chopper-type boost circuit, the windings are a first winding and a second winding among three windings provided in the generator, one end of the first winding and one end of the second winding are connected to a midpoint, and the other end of the second winding is connected to the rectifier circuit; the switch has a first state in which the other end of the first winding is connected to the power generation device and a second state in which the other end of the first winding is connected to the rectifier circuit; the control circuit controls the switch to the second state in the power generation mode and controls the switch to the first state in the converter mode; In the converter mode, the first winding and the second winding function as inductors in the chopper-type boost circuit. . [Effects of the Invention]

[0006] According to the present invention, it is possible to effectively utilize an engine generator provided as a backup power source for a power supply system even when the engine is stopped. [Brief explanation of the drawings]

[0007] [Figure 1] Diagram explaining the power supply system [Figure 2] Diagram explaining an engine generator [Figure 3] Diagram explaining the power supply system [Figure 4] Diagram explaining a step-up DC-DC converter [Figure 5] Diagram explaining a boost chopper circuit [Figure 6]Diagram explaining a step-up DC-DC converter [Figure 7] Diagram explaining the power supply system [Figure 8] Diagram explaining a step-up DC-DC converter [Figure 9] Diagram explaining a step-up DC-DC converter DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention as claimed, and not all combinations of features described in the embodiments are necessarily essential to the invention. Two or more of the features described in the embodiments may be arbitrarily combined. Furthermore, the same reference numerals are used for the same or similar components, and redundant explanations will be omitted.

[0009] <Power supply system> 1 shows an example of a power supply system 100. The power supply system 100 is, for example, an off-grid system that is disconnected from a commercial AC power supply. However, the power supply system 100 may also be a power supply system that is connected to or connectable to a commercial AC power supply.

[0010] The solar power generation system 101 is an example of a power generation system that uses renewable energy. The solar power generation system 101 can be replaced with other power generation systems that use renewable energy, such as a wind power generation system, a hydroelectric power generation system, and a tidal power generation system. The engine generator 102 is a backup power supply that uses the engine 1 to drive the generator 6 to generate electricity. During the period when the solar power generation system 101 can supply sufficient power, the engine 1 of the engine generator 102 is stopped.

[0011] The step-up DC-DC converter 104 is a step-up circuit that boosts the output voltage of the solar power generation system 101 to a specified voltage. The step-up DC-DC converter 104 performs the boosting operation by utilizing the coil of the generator 6. DC is an abbreviation for direct current.

[0012] The bidirectional inverter 103 is a conversion circuit that converts an input DC voltage into an AC voltage and outputs it to the AC input / output terminal 110, or converts an AC voltage input from the AC input / output terminal 110 into a DC voltage and outputs it. The input DC voltage is, for example, a DC voltage supplied from the engine generator 102, the step-up DC-DC converter 104, the bidirectional DC-DC converter 105, or the V2H charger 107. The DC voltage output from the bidirectional inverter 103 is supplied to the bidirectional DC-DC converter 105 or the V2H charger 107. V2H is an abbreviation for vehicle-to-home / home-to-vehicle. The V2H charger 107 may be a so-called bidirectional DC-DC converter that also has a discharge function for discharging from the vehicle to the home.

[0013] The bidirectional DC-DC converter 105 converts the DC voltage supplied from the bidirectional inverter 103 or the V2H charger 107 into a specified DC voltage and charges the power storage system 106. The bidirectional DC-DC converter 105 also converts the DC voltage supplied from the power storage system 106 into a specified DC voltage and supplies it to the bidirectional inverter 103 or the V2H charger 107.

[0014] The power storage system 106 has one or more batteries. The power storage system 106 mainly stores the power generated by the solar power generation system 101, but may also store a DC voltage supplied from the AC input / output terminal 110 via the bidirectional inverter 103 and the bidirectional DC-DC converter 105. The power storage system 106 may also store a DC voltage supplied from the engine generator 102 via the bidirectional inverter 103 and the bidirectional DC-DC converter 105. Furthermore, the power storage system 106 may also store a DC voltage supplied from the electric vehicle 108 via the V2H charger 107 and the bidirectional DC-DC converter 105.

[0015] The electric vehicle 108 is a vehicle capable of supplying electric power to the outside, such as a plug-in hybrid vehicle (PHeV) or a fuel cell vehicle (FCV).

[0016] <Engine system> FIG. 2 is a schematic diagram of an engine generator 102. Engine 1 is a four-stroke internal combustion engine. Engine 1 may be a hydrogen engine that uses hydrogen as fuel. Crankcase 2 houses crankshaft 19. As crankshaft 19 rotates, piston 4, connected to connecting rod 3, moves up and down within the cylinder. A recoil starter 5 for starting engine 1 is connected to crankshaft 19. A recoil operator rotates crankshaft 19 by grasping and pulling the handle of recoil starter 5. Note that a starter motor powered by a battery may be used as a starting device instead of recoil starter 5. A generator 6 is connected to crankshaft 19, and as crankshaft 19 rotates, the rotor of generator 6 rotates to generate electricity. The crank angle of crankshaft 19 is detected by crank angle sensor 7. Crank angle sensor 7 may be, for example, a Hall element that detects the magnetism of a magnet provided on a flywheel connected to crankshaft 19. The power supply circuit 8 includes an inverter that converts the AC generated by the generator 6 into AC with a constant frequency, a circuit that converts AC to DC, and a circuit that converts the level of the DC voltage. The power supply circuit 8 may also include a battery that supplies power to the control unit 9a. This allows the power supply circuit 8 to supply the power generated by the generator 6 to the control unit 9a. When the recoil starter 5 rotates the crankshaft 19, the generator 6 generates enough power to operate the control unit 9a. The control unit 9a is an engine control unit (ECU) that controls the power supplied from the power supply circuit 8 to the ignition device 11, fuel pump 14, injector 15, throttle motor 16, and other components. The ignition device 11 supplies ignition power to the spark plug 12 to generate a spark. The fuel tank 13 is a container that contains fuel. The fuel pump 14 supplies fuel contained in the fuel tank 13 to the injector 15. In FIG. 1, the fuel pump 14 is located inside the fuel tank. The throttle motor 16 is a motor for controlling the amount of air flowing into the cylinder via the intake path 50 .The intake valve 17 is a valve that opens and closes by a cam or the like that converts the rotational motion of the crankshaft 19 into up and down motion. The intake valve 17 opens during the intake stroke and is basically closed during the compression stroke, expansion stroke, and exhaust stroke. The exhaust valve 18 is a valve that opens and closes by a cam or the like that converts the rotational motion of the crankshaft 19 into up and down motion. The exhaust valve 18 opens during the exhaust stroke and is basically closed during the compression stroke, expansion stroke, and intake stroke. To smooth the transition from exhaust to intake, a period may be set during which the intake valve 17 and exhaust valve 18 are open simultaneously (overlap). The CO sensor 41 is a sensor that detects the concentration of carbon monoxide (CO) in the exhaust gas discharged from the cylinder to the exhaust path 51.

[0017] <Details of the step-up DC-DC converter> 3 shows an example of connection of the photovoltaic power generation system 101 to the engine generator 102. In this example, the photovoltaic power generation system 101 has a single photovoltaic power generation device PVa. The DC voltage generated by the photovoltaic power generation device PVa is connected to one of the three-phase windings of the generator 6. The bidirectional DC-DC converter 105 may have multiple DC-DC converters 303a, 302b. The power storage system 106 has multiple batteries 302a, 302b. The DC-DC converter 303a is connected to the battery 302a and converts the DC voltage supplied from the battery 302a into a specified DC voltage (discharge mode), and converts the DC voltage supplied from the generator 6 or the bidirectional inverter 103 into a specified DC voltage and supplies it to the battery 302a (charge mode). The DC-DC converter 303b is connected to the battery 302b and converts the DC voltage supplied from the battery 302b into a specified DC voltage (discharge mode), and converts the DC voltage supplied from the generator 6 or the bidirectional inverter 103 into a specified DC voltage and supplies it to the battery 302b (charge mode). Although two sets of batteries and DC-DC converters are shown here, this is merely an example. The number of sets of batteries and DC-DC converters may be one, or three or more.

[0018] FIG. 4 shows the details of the step-up DC-DC converter 104. The generator 6 is a three-phase AC generator and has a U-phase winding LU, a V-phase winding LV, and a W-phase winding LW. A rectifier circuit 300 is connected to the generator 6, converting the AC generated by the generator 6 into a pulsating current. The rectifier circuit 300 has a bridge circuit in which six FETs Q1 to Q6 are bridge-connected. In other words, the rectifier circuit 300 functions as a synchronous rectifier circuit. FET is an abbreviation for field-effect transistor. The FETs Q1 to Q6 are, for example, MOS (metal-oxide semiconductor) type FETs, but other types of switching elements may also be used. The drain terminals of the FETs Q1, Q2, and Q3 are connected to one end of a capacitor C1. The source terminal of the FET Q1 is connected to one end of the winding LU and the drain terminal of the FET Q4. The source terminal of the FET Q4 is connected to the other end of the capacitor C1 and the solar power generation device PVa. The source terminal of FET Q2 is connected to one end of winding LV and the drain terminal of FET Q5. The source terminal of FET Q5 is connected to the other end of capacitor C1 and solar power generation device PVa. The source terminal of FET Q3 is connected to one end of winding LW and the drain terminal of FET Q6. The source terminal of FET Q6 is connected to the other end of capacitor C1 and solar power generation device PVa. A control signal is applied from CPU 305 to the gate terminals of FETs Q1 to Q6. This turns FETs Q1 to Q6 on and off, and the currents generated in windings LU, LV, and LW are rectified in order to become pulsating currents. The pulsating currents charge capacitor C1 in smoothing circuit 301. In other words, the pulsating currents are converted to direct current by capacitor C1.

[0019] The inverter circuit of the bidirectional inverter 103 is composed of four FETs Q7 to Q10. The drain terminal of FET Q7 and the drain terminal of FET Q8 are connected to one end of the capacitor C1. The source terminal of FET Q7 and the drain terminal of FET Q9 are connected to a line filter 310. The source terminal of FET Q8 and the drain terminal of FET Q10 are connected to the line filter 310. The source terminal of FET Q9 and the source terminal of FET Q10 are connected to the other end of the capacitor C1. A control signal is applied from the CPU 305 to the gate terminals of FETs Q7 to Q10. This turns on / off the FETs Q7 to Q10, and the voltage across the capacitor C1 is converted into an AC voltage. A line filter 310 may be provided downstream of the bidirectional inverter 103. The line filter 310 cuts out unnecessary high-frequency components contained in the AC voltage.

[0020] The CPU 305 is mounted on the control unit 9a and controls the engine generator 102 in accordance with a control program stored in the ROM area of the memory 306. ROM is an abbreviation for read-only memory and is a non-volatile storage device. The memory 306 also has RAM (random access memory) as a volatile storage device. When the engine 1 is running and the generator 6 is generating power, the CPU 305 turns off the switch SW.

[0021] On the other hand, while the engine 1 is stopped, the CPU 305 turns on the switch SW and applies the DC voltage supplied from the photovoltaic power generation device PVa to the midpoint of the windings LU, LV, and LW. As an example, it is assumed that the winding LU is used as an inductor of a chopper-type boost circuit.

[0022] FIG. 5 shows an example of a chopper-type boost circuit using a winding LU. One end of the winding LU is connected to a photovoltaic power generator PVa via a switch SW. The other end of the winding LU is connected to the drain terminal of an FET Q4. FETs Q1 to Q6 have parasitic diodes. Here, the parasitic diode of FET Q1 is referred to as diode D1. When the FET Q4 is on, current flows from the photovoltaic power generator PVa to the winding LU. The current also flows from the winding LU to the drain terminal of the FET Q4, flows out of the source terminal, and returns to the photovoltaic power generator PVa. This stores energy in the winding LU. When the FET Q4 is off, a current is generated by the energy stored in the winding LU, passes through diode D1, and charges capacitor C1. Repeated on-off switching of the FET Q4 generates an output voltage higher than the input voltage. The step-up ratio E is defined by the switching period T of the FET Q4, the period Ton during which the FET Q4 is on, and the period Toff during which the FET Q4 is off (E=T / Toff, where T=Ton+Toff). That is, by the CPU 305 controlling the on-period Ton, any output voltage can be generated. For example, the CPU 305 sets the on-period Ton so that the output voltage of the step-up DC-DC converter 104 satisfies the conditions required as the input voltage of the bidirectional inverter 103.

[0023] The output voltage of the photovoltaic power generation device PVa changes depending on the weather. Therefore, the CPU 305 detects the voltage Vc1 across the capacitor C1 and varies the on-period Ton in accordance with the voltage Vc1 across the capacitor C1, thereby controlling the output voltage of the step-up DC-DC converter 104 to be constant.

[0024] In this example, a chopper boost circuit is formed by the winding LU, the parasitic diode (diode D1) of FET Q1, FET Q4, and capacitor C1, but this is merely an example. As can be seen from Figure 4, a chopper boost circuit may also be formed by the winding LV, the parasitic diode of FET Q2, FET Q5, and capacitor C1. Similarly, a chopper boost circuit may also be formed by the winding LW, the parasitic diode of FET Q3, FET Q6, and capacitor C1.

[0025] The CPU 305 may realize a chopper boost circuit (boost chopper circuit) using one predetermined winding, or may realize a chopper boost circuit using two or more windings. For example, the windings LU, LV, and LW may be used in order as a chopper boost circuit, or the windings LU, LV, and LW may be used simultaneously in parallel as a chopper boost circuit.

[0026] FIG. 6 shows a modification of the step-up DC-DC converter 104 shown in FIG. 4. Due to design constraints on the generator 6, it may not be possible to connect one end of the switch SW to the midpoint of the windings LU, LV, and LW. In this case, the circuit configuration shown in FIG. 6 is useful. That is, a single-circuit, two-contact switch is used as the switch SW. When the windings LU, LV, and LW are used as inductors in a chopper-type boost circuit, the CPU 305 controls the switch SW to connect one end of the winding LV to the photovoltaic power generation device Pva. That is, the contact a of the switch SW is closed. On the other hand, when the windings LU, LV, and LW are not used as inductors in a chopper-type boost circuit (that is, when the engine 1 is operating), the CPU 305 controls the switch SW to connect one end of the winding LV to the midpoint between the FETs Q6 and Q3. That is, the contact b of the switch SW is closed.

[0027] 6, a chopper boost circuit is formed by the windings LW and LU, the parasitic diode of FET Q1, FET Q4, and capacitor C1. Also, a chopper boost circuit is formed by the windings LW and LV, the parasitic diode of FET Q2, FET Q5, and capacitor C1.

[0028] <Case where generator 6 is connected to multiple solar power generation devices> 7 shows a case where a generator 6 is connected to three photovoltaic power generators PVa, PVb, and PVc. In other words, the photovoltaic power generation system 101 has three independent photovoltaic power generators PVa, PVb, and PVc. The photovoltaic power generators PVa, PVb, and PVc are connected to a chopper-type boost circuit that uses one of three windings LU, LV, and LW.

[0029] Figure 8 shows a modified example of step-up DC-DC converter 104. A single-pole, two-contact switch SWa is connected to one end of winding LU. A photovoltaic power generator PVa is connected to the a-contact of switch SWa. One end of winding LV is connected to the b-contact of switch SWa. A single-pole, two-contact switch SWb is also connected to one end of winding LV. A photovoltaic power generator PVb is connected to the a-contact of switch SWb. One end of winding LW is connected to the b-contact of switch SWb. One end of winding LW is also connected to a single-pole, one-contact switch SWc. Switch SWc is connected between photovoltaic power generator PVc and winding LW.

[0030] When the generator 6 is in a power generation mode driven by the engine 1 to generate power, the CPU 305 switches the switches SWa and SWb to contact b, and switches the switch SWc to OFF. This causes the windings LU, LV, and LW to function as three-phase windings of the generator 6. The photovoltaic power generation devices PVa, PVb, and PVc are disconnected from the step-up DC-DC converter 104.

[0031] When the engine 1 is stopped (converter mode), the CPU 305 switches the switches SWa and SWb to contacts a and turns on the switch SWc. This connects the photovoltaic power generation devices PVa, PVb, and PVc to the corresponding windings LU, LV, and LW, respectively. The windings LU, LV, and LW function as coils of the chopper-type boost circuit shown in FIG. 5.

[0032] As shown in FIG. 8, the drain of FET Q1 is connected to the source of FET Q11 of switch circuit 800. The drain of FET Q2 is connected to the source of FET Q12 of switch circuit 800. The drain of FET Q3 is connected to the source of FET Q13 of switch circuit 800. The drains of FET Q11, Q12, and Q13 are all connected to one end of capacitor C1. In power generation mode, CPU 305 outputs control signals to the gates of FET Q11, Q12, and Q13 to turn on FETs Q11, Q12, and Q13, respectively. In converter mode, CPU 305 turns off FETs Q11, Q12, and Q13, respectively, and keeps FETs Q1, Q2, and Q3 on, respectively. During the boost period in converter mode, CPU 305 turns on FETs Q4, Q5, and Q6, respectively. As a result, current flows through the windings LU, LV, and LW from the corresponding photovoltaic power generators PVa, PVb, and PVc, respectively, and energy is stored. During the release period in converter mode, the CPU 305 turns off the FETs Q4, Q5, and Q6, respectively. As a result, the windings LU, LV, and LW release energy, and current flows through the corresponding parasitic diodes of the FETs Q11, Q12, and Q13. In other words, the parasitic diodes of the FETs Q11, Q11, Q12, and Q13 function as diode D1 in the chopper boost circuit shown in FIG. 5.

[0033] In converter mode, variations may occur in the boost voltages Vc1a, Vc1b, and Vc1c of the photovoltaic power generators PVa, PVb, and Pvc. In this case, the CPU 305 detects the boost voltages Vc1a, Vc1b, and Vc1c and controls the boost ratios Ea, Eb, and Ec of the boost voltages Vc1a, Vc1b, and Vc1c so that the boost voltages Vc1a, Vc1b, and Vc1c are equal to their respective target voltages. The boost ratios Ea, Eb, and Ec of the boost voltages Vc1a, Vc1b, and Vc1c can be set by controlling the ratio between the on-period and the off-period of the corresponding FETs Q4, Q5, and Q6. The CPU 305 controls the ratio between the on-period and the off-period of the FETs Q4, Q5, and Q6 so that the boost voltages Vc1a, Vc1b, and Vc1c are equal to their respective target voltages.

[0034] As shown in Fig. 9, the technical concept of the embodiment may be applied to two photovoltaic power generation devices PVa and PVb. In this case, the photovoltaic power generation device PVc shown in Fig. 8 is not present, and therefore the switch SWc and FET Q13 are not required. The circuit operation in Fig. 9 is basically the same as the circuit operation in Fig. 8.

[0035] <Technical ideas derived from examples> [Point 1] Photovoltaic power generation systems PV, PVa to PVc, wind power generation systems, and hydroelectric power generation systems are examples of power generation systems that use renewable energy. Lowercase letters added to reference symbols may be omitted.

[0036] The engine generator 102 is an example of an engine generator. An engine generator is basically not a vehicle operated by a human being, but an engine generator that does not require human intervention. For example, the engine generator may have a handle that can be grasped by a human hand and be transportable by a human being. The switches SW, SWa to SWc are examples of switches that connect the power generation device and the engine generator 102. The CPU 305 is an example of a control circuit that controls the switches. The CPU 305 may also be called a processor, a processing circuit, or a central processing unit. The control circuit may be implemented using an ASIC (application-specific integrated circuit) or an FPGA (field-programmable gate array), etc.

[0037] The generator 6 is an example of a generator including windings (e.g., windings LU, LV, and LW). The generator 6 may also be called an alternator. The engine 1 is an example of an engine that drives the generator 6. The rectifier circuit 300 is an example of a rectifier circuit that is connected to the generator 6 and has a plurality of switch elements (e.g., FETs Q1 to Q6) that rectify the alternating current generated in the windings. The smoothing circuit 301 is an example of a smoothing circuit that smoothes the pulsating current output from the rectifier circuit 300.

[0038] The control circuit has a power generation mode in which the generator 6 of the engine generator 102 is driven by the engine to generate power. In the power generation mode, the control circuit controls the switch SW to disconnect the power generation device from the engine generator 102. Furthermore, the control circuit controls a plurality of switch elements to cause the rectifier circuit 300 to rectify the AC.

[0039] The control circuit has a converter mode in which the generator 6 of the engine generator 102 does not generate power. In the converter mode, the control circuit controls the switch SW to connect the power generation device to the engine generator 102. The converter mode includes a boost period in which the voltage supplied from the power generation device is boosted and a discharge period in which energy stored in the winding is discharged. The control circuit controls multiple switch elements to store energy supplied from the power generation device in the winding during the boost period. The control circuit controls multiple switch elements to discharge the energy stored in the winding to the smoothing circuit 301 during the discharge period. As described above, according to this embodiment, the engine generator 102, which is provided as a backup power supply for the power supply system, can be effectively utilized even when the engine 1 is stopped. For example, the windings LU, LV, and LW of the generator 6 can be used as part of the boost circuit. As a result, a boost-type DC-DC converter that is previously provided exclusively for a power generation device such as a photovoltaic power generation device PV can be omitted.

[0040] [Point 2] 5, in the converter mode, the windings LU, LV, and LW, the capacitor C1 of the smoothing circuit 301, and at least two of the multiple switch elements (e.g., FET Q1 and FET Q4) form a chopper-type boost circuit. That is, the windings LU, LV, and LW are used as inductors of the chopper-type boost circuit.

[0041] [Point 3] The control circuit controls the boost ratio E of the boost circuit by controlling the on-period and off-period of a first switch element (e.g., FET Q4) among at least two switch elements. This makes it possible to realize any boost ratio E. For example, it becomes possible to adjust the boost voltage so as to achieve a voltage level required as an input to the inverter 103 in the subsequent stage.

[0042] [Point 4] In converter mode, the control circuit maintains off a second switch element (e.g., FET Q1) connected to a first switch element (e.g., FET Q4) among the at least two switch elements. Furthermore, the control circuit discharges energy from the winding via a parasitic diode D1 of the second switch element during a discharge period. In this manner, the parasitic diode D1 of the second switch element may be used as a diode forming a boost circuit. However, instead of the parasitic diode D1, an independent diode connected to the drain and source of the switch element may be employed.

[0043] [Point 5] 4 and the like, the switch SW may be connected to the midpoint of three windings provided in the generator 6. The generator 6 may be called a three-phase AC generator.

[0044] [Point 6] As illustrated in FIG. 6, the windings of the boost circuit may be a first winding (e.g., LW) and a second winding (e.g., LU and LV) among three windings provided in the generator 6. One end of the first winding and one end of the second winding are connected to a midpoint. The other end of the second winding is connected to the rectifier circuit 300. The switch SW has a first state in which the other end of the first winding is connected to the power generation device and a second state in which the other end of the first winding is connected to the rectifier circuit 300. The control circuit controls the switch SW to the second state in the power generation mode. The control circuit controls the switch SW to the first state in the converter mode. In the converter mode, the first winding and the second winding function as inductors in a chopper-type boost circuit.

[0045] [Point 7] The photovoltaic power generation devices PVa, PVb, and PVc are examples of a first power generation device, a second power generation device, and a third power generation device that generate electricity using renewable energy. The switch SWa is an example of a first switch that connects the first power generation device and the engine generator. The switch SWb is an example of a second switch that connects the second power generation device and the engine generator. The switch SWc is an example of a third switch that connects the third power generation device and the engine generator. The CPU 305 is an example of a control circuit that controls the first switch, the second switch, and the third switch.

[0046] The generator 6 having windings LU, LV, and LW is an example of a generator including a first winding, a second winding, and a third winding. The engine 1 is an example of an engine that drives the generator 6. The rectifier circuit 300 is an example of a rectifier circuit that is connected to the generator and has a plurality of switch elements that rectify the alternating current generated in the first winding, the second winding, and the third winding, respectively.

[0047] In the power generation mode, the control circuit controls the first switch, the second switch, and the third switch to disconnect the first power generation device, the second power generation device, and the third power generation device from the engine generator, and controls multiple switch elements to rectify the AC using the rectifier circuit.

[0048] The control circuit controls the first switch, the second switch, and the third switch in the converter mode to connect the first power generator, the second power generator, and the third power generator to the engine generator. Further, the control circuit stores energy supplied from the first power generator, the second power generator, and the third power generator in the corresponding first winding, the second winding, and the third winding during a boost period in which the control circuit boosts voltages supplied from the first power generator, the second power generator, and the third power generator. The control circuit controls the multiple switch elements to release the energy stored in the first winding, the second winding, and the third winding to the smoothing circuit during a release period.

[0049] [Point 8] The first switch connects the first generator to the first winding in the converter mode and disconnects the first generator from the first winding and connects the first winding to the neutral point in the generating mode. The second switch connects the second generator to the second winding in the converter mode and disconnects the second generator from the second winding and connects the second winding to the neutral point in the generating mode. The third switch connects the third generator to the third winding in the converter mode and disconnects the third generator from the third winding and connects the third winding to the neutral point in the generating mode.

[0050] [Point 9] In the converter mode, the first winding, the capacitor of the smoothing circuit, and a first switch element (e.g., FET Q4) and a second switch element (e.g., FET Q1, FET Q11) among the multiple switch elements form a chopper-type boost circuit for the first power generator. The second winding, the capacitor of the smoothing circuit, and a third switch element (e.g., FET Q5) and a fourth switch element (e.g., FET Q2, FET Q12) among the multiple switch elements form a chopper-type boost circuit for the second power generator. The third winding, the capacitor of the smoothing circuit, and a fifth switch element (e.g., FET Q6) and a sixth switch element (e.g., FET Q3, FET Q13) among the multiple switch elements form a chopper-type boost circuit for the third power generator.

[0051] [Point 10] The control circuit controls the boost ratio of a chopper-type boost circuit for a first power generator by controlling the on and off periods of a first switch element (e.g., FET Q4) connected to the second switch element. The control circuit controls the boost ratio of a chopper-type boost circuit for a second power generator by controlling the on and off periods of a third switch element (e.g., FET Q5) connected to the fourth switch element. The control circuit controls the on and off periods of a fifth switch element (e.g., FET Q6) connected to the sixth switch element, thereby controlling the boost ratio of a chopper-type boost circuit for a third power generator.

[0052] [Point 11] The FET Q11 is an example of a seventh switch element connected between the second switch element and the capacitor. The FET Q12 is an example of an eighth switch element connected between the fourth switch element and the capacitor. The FET Q13 is an example of a ninth switch element connected between the sixth switch element and the capacitor. The control circuit turns on the first switch element and keeps the seventh switch element off during a boost period in the converter mode. The control circuit turns off the first switch element and causes energy to be discharged from the first winding through a parasitic diode of the seventh switch element during a discharge period. The control circuit turns on the third switch element and keeps the eighth switch element off during a boost period in the converter mode. The control circuit turns off the third switch element and causes energy to be discharged from the second winding through a parasitic diode of the eighth switch element during a discharge period. The control circuit turns on the fifth switch element and keeps the ninth switch element off during a boost period in the converter mode. The control circuit turns off the fifth switch element and causes energy to be discharged from the third winding through a parasitic diode of the ninth switch element during a discharge period.

[0053] In converter mode, FETs Q1, Q2, and Q3 may be kept off. In this case, the parasitic diodes of FETs Q1, Q2, and Q3 are connected in series with the parasitic diodes of FETs Q11, Q12, and Q13, and function as diode D1 of the boost circuit. In converter mode, FETs Q1, Q2, and Q3 may be kept on. In this case, the parasitic diodes of FETs Q11, Q12, and Q13 function as diode D1 of the boost circuit.

[0054] [Point 12] The control circuit controls the ratio between the on period and the off period of the first switch element, the ratio between the on period and the off period of the third switch element, and the ratio between the on period and the off period of the fifth switch element so that the boost voltage for the first power generator, the boost voltage for the second power generator, and the boost voltage for the third power generator are each equal to a target voltage, thereby making it possible to absorb variations in the outputs of the three power supply devices.

[0055] The invention is not limited to the above-described embodiment, and various modifications and variations are possible within the scope of the gist of the invention. [Explanation of symbols]

[0056] 100: power supply system, PV: photovoltaic power generation device, 102: engine generator, LU: winding, SW: switch, 305: CPU, 6: generator (alternator), FET Q1 to FET Q6: switching elements, 300: rectifier circuit, 301: smoothing circuit

Claims

1. 1. A power supply system, comprising: a power generation device that generates electricity using renewable energy; An engine generator, a switch that connects the power generation device and the engine generator; a control circuit for controlling the switch; The engine generator includes: a generator including a winding; an engine that drives the generator; a rectifier circuit connected to the generator and having a plurality of switch elements for rectifying the alternating current generated in the winding; a smoothing circuit that smoothes the pulsating current output from the rectifier circuit, The control circuit In a power generation mode in which the generator of the engine generator is driven by the engine to generate power, the switch is controlled to disconnect the power generation device from the engine generator, and the AC is rectified by the rectifier circuit by controlling the plurality of switch elements; in a converter mode in which the generator of the engine generator does not generate power, controlling the switches to connect the power generation device to the engine generator, and controlling the plurality of switch elements so as to store energy supplied from the power generation device in the winding during a boost period in which the voltage supplied from the power generation device is boosted, and to release the energy stored in the winding to the smoothing circuit during a release period; in the converter mode, the winding, a capacitor of the smoothing circuit, and at least two switch elements among the plurality of switch elements form a chopper-type boost circuit, the windings are a first winding and a second winding among three windings provided in the generator, one end of the first winding and one end of the second winding are connected to a midpoint, and the other end of the second winding is connected to the rectifier circuit; the switch has a first state in which the other end of the first winding is connected to the power generation device and a second state in which the other end of the first winding is connected to the rectifier circuit; the control circuit controls the switch to the second state in the power generation mode and controls the switch to the first state in the converter mode; In the converter mode, the first winding and the second winding function as inductors in the chopper-type boost circuit.

2. 2. The power supply system of claim 1, The control circuit controls a period during which a first switch element of the at least two switch elements is on and a period during which the first switch element is off, thereby controlling a boost ratio of the boost circuit.

3. 3. The power supply system according to claim 2, the control circuit, in the converter mode, keeps off a second switch element, of the at least two switch elements, connected to the first switch element, and discharges energy from the winding via a parasitic diode of the second switch element during the discharge period.

4. 4. The power supply system according to claim 1, The switch is connected to the midpoint of three windings of the generator.

5. 1. A power supply system, comprising: a first power generating device, a second power generating device, and a third power generating device that generate electricity using renewable energy; An engine generator, a first switch that connects the first power generation device and the engine generator; a second switch that connects the second power generation device and the engine generator; a third switch connecting the third power generation device and the engine generator; a control circuit for controlling the first switch, the second switch, and the third switch; The engine generator includes: a generator including a first winding, a second winding, and a third winding; an engine that drives the generator; a rectifier circuit connected to the generator and having a plurality of switch elements for rectifying the alternating current generated in each of the first winding, the second winding, and the third winding; a smoothing circuit that smoothes the pulsating current output from the rectifier circuit, The control circuit In a power generation mode in which the generator of the engine generator is driven by the engine to generate power, the first switch, the second switch, and the third switch are controlled to disconnect the first power generation device, the second power generation device, and the third power generation device from the engine generator, and the AC is rectified by the rectifier circuit by controlling the plurality of switch elements; a power supply system that controls the first switch, the second switch, and the third switch to connect the first power generation device, the second power generation device, and the third power generation device to the engine generator in a converter mode in which the generator of the engine generator does not generate power; and controls the plurality of switch elements to store energy supplied from the first power generation device, the second power generation device, and the third power generation device in the corresponding first winding, the second winding, and the third winding, respectively, during a boost period in which voltages supplied from the first power generation device, the second power generation device, and the third power generation device are boosted; and controls the plurality of switch elements to release the energy stored in the first winding, the second winding, and the third winding, respectively, to the smoothing circuit during a release period.

6. 6. The power supply system according to claim 5, the first switch connects the first power generation device and the first winding in the converter mode, and disconnects the first power generation device and the first winding and connects the first winding to a neutral point in the power generation mode; the second switch connects the second power generator and the second winding in the converter mode, and disconnects the second power generator and the second winding and connects the second winding to the neutral point in the power generation mode; the third switch connects the third power generation device and the third winding in the converter mode, and disconnects the third power generation device and the third winding and connects the third winding to the neutral point in the power generation mode.

7. 6. The power supply system according to claim 5, In the converter mode, the first winding, a capacitor of the smoothing circuit, and a first switch element and a second switch element among the plurality of switch elements form a chopper-type boost circuit for the first power generation device, the second winding, the capacitor of the smoothing circuit, and a third switch element and a fourth switch element among the plurality of switch elements form a chopper-type boost circuit for the second power generation device, the third winding, the capacitor of the smoothing circuit, and a fifth switch element and a sixth switch element among the plurality of switch elements form a chopper-type boost circuit for the third power generation device.

8. 8. The power supply system of claim 7, The control circuit a step-up ratio of the chopper-type step-up circuit for the first power generator is controlled by controlling an on period and an off period of the first switch element connected to the second switch element; a boost ratio of the chopper boost circuit for the second power generator is controlled by controlling an on period and an off period of the third switch element connected to the fourth switch element; a power supply system in which a boost ratio of the chopper boost circuit with respect to the third power generation device is controlled by controlling an on period and an off period of the fifth switch element connected to the sixth switch element.

9. 9. The power supply system of claim 8, a seventh switch element connected between the second switch element and the capacitor; an eighth switch element connected between the fourth switch element and the capacitor; a ninth switch element connected between the sixth switch element and the capacitor, The control circuit during the boost period in the converter mode, turning on the first switch element and maintaining the seventh switch element in an off state, and during the discharge period, turning off the first switch element and discharging energy from the first winding through a parasitic diode of the seventh switch element; during the boost period in the converter mode, turning on the third switch element and maintaining the eighth switch element in an off state, and during the discharge period, turning off the third switch element and discharging energy from the second winding through a parasitic diode of the eighth switch element; the fifth switch element is turned on and the ninth switch element is kept off during the boost period in the converter mode, and the fifth switch element is turned off during the discharge period to discharge energy from the third winding via a parasitic diode of the ninth switch element.

10. 10. The power supply system of claim 9, the control circuit controls a ratio between an on period and an off period of the first switch element, a ratio between an on period and an off period of the third switch element, and a ratio between an on period and an off period of the fifth switch element so that a boost voltage for the first power generation device, a boost voltage for the second power generation device, and a boost voltage for the third power generation device are each equal to a target voltage.

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