JP2014033552A - Power circuit and power conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power circuit and power conditioner capable of achieving further miniaturization of a power transformer.SOLUTION: The power circuit 10 includes: a power transformer 60; a first gate power circuit 64 that converts an AC power supply from one secondary winding 63 of a plurality of secondary windings into a DC power supply; a switching circuit 71; a plurality of pulse transformers 72-1 to 72-n that are connected in parallel to the output side of the switching circuit 71, are provided by the number corresponding to the number of respective switching elements and insulate high-frequency power converted by the switching circuit 71 for output; and a plurality of second rectification circuits 73-1 to 73-n and a plurality of second smoothing circuits 74-1 to 74-n that convert AC power supply from the respective pulse transformers 72-1 to 72-n into DC power supply and output the DC power supply as gate power supply.

Description

  The present invention relates to a power supply circuit and a power conditioner for photovoltaic power generation provided with the power supply circuit.

  In recent years, there has been an increasing interest in reducing CO2 emissions that cause global warming, and alternative energy for fossil fuels that are expected to be depleted. Solar energy is a clean and inexhaustible energy source. The solar power generation system by is attracting attention.

  In a photovoltaic power generation system, a power conditioner that converts direct-current power generated by a solar cell module into alternating-current power that can be used by a general electric device is an important component. This power conditioner includes a single-phase output type suitable for residential use, a three-phase output type suitable for public facilities and business use, and types according to installation locations such as indoor use and outdoor use.

  In the power conditioner as described above, an inverter circuit for converting DC power into AC power is mounted. As an inverter circuit, as shown in Patent Document 1, a switching element such as an IGBT having a bridge configuration is known, and each switching element in the bridge is turned ON / OFF in a predetermined pattern. An AC output waveform is generated. The switching element is turned on / off by a control signal to the gate of the switching element and supply of power to drive the gate of the switching element.

JP 2002-199743 A (FIG. 1 etc.)

  The prior art disclosed in Patent Document 1 requires as many gate power supply circuits as the number of gates of the switching element. This is because the gate power supply must be configured independently because the potential of each switching element is different. In addition, although it is possible to devise a means such as combining parts with a common potential with one power supply, basically, gate power supply circuits are required as many as the number of gates. In the prior art, power such as a system or solar cell output is supplied to the primary side of the power transformer, and a plurality of gate power circuits are provided on the secondary side of the power transformer. Further, on the secondary side of the power transformer, another control power source (for example, a power source of a control circuit for controlling the operation of the inverter circuit) is also provided.

  Here, since a plurality of gate power supply circuits are necessary as described above, the types of secondary windings (the number of secondary windings) of the power transformer increase accordingly. Further, since the potential of these secondary windings becomes the potential of the switching element portion of the main circuit, it is necessary to ensure the winding insulation performance and the insulation distance of the output terminal of the power transformer. Accordingly, since the power transformer needs to have a certain size, the power transformer has a problem that the degree of freedom of the arrangement position of the gate power circuit is restricted.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a power supply circuit and a power conditioner that can further reduce the size of a power transformer.

  In order to solve the above-described problems and achieve the object, the present invention is a power supply circuit that supplies at least a gate power supply that drives a plurality of switching elements included in a main circuit, and includes a primary side winding and a plurality of secondary power supplies. A power transformer having a secondary winding and a first transformer which is connected to one secondary winding in each of the secondary windings and converts an AC power supply from the secondary winding into a DC power supply. Power switching circuit, a switching circuit for switching a DC power source from the first power conversion circuit, connected in parallel to the output side of the switching circuit, and provided in a number corresponding to each switching element, A plurality of pulse transformers that insulate and output the high-frequency power converted by the switching circuit, and connected to the secondary side of each pulse transformer, and an AC power source from each pulse transformer is a DC power source Conversion, characterized in that the DC power source and a plurality of second power conversion circuit to output as the gate power supply.

  According to this invention, since the plurality of gate power supplies are provided on the output side of one secondary winding in the plurality of secondary windings provided in the power transformer, further miniaturization of the power transformer is achieved. There is an effect that can be achieved.

FIG. 1 is a diagram illustrating a configuration of a photovoltaic power generation system including a power conditioner according to an embodiment. FIG. 2 is a diagram showing an internal configuration of the power supply circuit shown in FIG. FIG. 3 is a diagram schematically showing a substrate on which a power supply circuit and the like are mounted.

  Embodiments of a power supply circuit and a power conditioner according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment.
FIG. 1 is a diagram illustrating a configuration of a photovoltaic power generation system 100 including a power conditioner 1 according to an embodiment, and FIG. 2 is a diagram illustrating an internal configuration of the power supply circuit 10 illustrated in FIG. 3 is a diagram schematically showing a substrate on which a power supply circuit and the like are mounted.

  First, the whole structure of the solar power generation system 100 is demonstrated using FIG. The photovoltaic power generation system 100 includes solar cell modules 11, 12, 13, 14, 15 and a power conditioner 1. Further, the power conditioner 1 includes DC switches 31, 32, 33, a collective DC switch 35, a noise filter 2, a booster circuit 4, a balance circuit 6, an inverter circuit 7, a filter circuit 8, a noise filter 9, an interconnection MC 51, A self-supporting MC 52, a power supply circuit 10, a control circuit 20, a gate circuit 30, and a display unit 40 are included.

  The solar cell modules 11 to 15 installed on the roof generate direct current power by receiving sunlight, but the voltage value per one is about 20 or 30 V, and it is difficult to use as it is, so the number of modules About 10 to a dozen or more sheets are connected in series, and the DC voltage per series unit (strings) is increased. The output cable from each string is connected to a plurality of input terminal blocks 21, 22, 23, 24, 25 provided in the power conditioner 1.

  These output cables are connected to the DC switches 31 to 33 in units of one set of input terminal blocks (1 string) or two sets of input terminal blocks (2 strings). Further, backflow prevention diodes 41, 42, 43, 44, 45 are inserted between the input terminal blocks 21-25 and the DC switches 31-33 in units of input terminal blocks (string units). The backflow prevention diodes 41 to 45 prevent the power stored in the input capacitor 3 from backflowing when the output of the solar cell modules 11 to 15 is lowered, and for preventing damage due to reverse connection of the strings. Is. Further, the output sides of these DC switches 31 to 33 are grouped together and connected to the input of the collective DC switch 35.

  On the output side of the collective DC switch 35, a noise filter 2, an input capacitor 3, a booster circuit 4, and a bus capacitor 5 are connected in order. The booster circuit 4 is composed of an inductance, a switch element, a diode, a capacitor, and the like. The booster circuit 4 employs a multi-level chopper method as an example. The bus capacitor 5 has a configuration in which two capacitors are connected in series, and a balance circuit 6 composed of a switch element and a reactor is connected between the booster circuit 4 and the bus capacitor 5.

  The inverter circuit 7, the filter circuit 8, and the noise filter 9 are sequentially connected to the next stage of the bus capacitor 5. The inverter circuit 7 is, for example, a three-level inverter, and the filter circuit 8 includes a reactor and a capacitor. The output side of the noise filter 9 is divided into two systems, one connected to the interconnected MC 51 and the other connected to the self-supporting MC 52. The output of the interconnecting MC 51 is connected to the power system (three-phase in this embodiment) via the interconnecting terminal block 53, and the output of the self-supporting MC 52 is connected to the load via the self-supporting terminal block 54.

  The power supply circuit 10 has an input side connected to a DC voltage section (such as both ends of the input capacitor 3), and an output side connected to various circuits such as the control circuit 20, the gate circuit 30, and the display unit 40, and is supplied to these various circuits. Generate power. In the control circuit 20, a control command for controlling the balance circuit 6, the inverter circuit 7, the interconnection MC 51, and the self-supporting MC 52 is generated, and the gate circuit 30 is based on the control command from the control circuit 20. And the gate signal which drives the gate of each switching element of the inverter circuit 7 is produced | generated. These various circuits are connected to relevant locations in the inverter 1. The display unit 40 displays the instantaneous value and integrated power amount of the generated power generated by the solar power generation system 100. The user can grasp the operation status of the photovoltaic power generation system 100 based on the information displayed on the display unit 40.

  Next, the operation of the photovoltaic power generation system 100 will be described. The DC power of the solar cell modules 11 to 15 is temporarily stored in the input capacitor 3 via the DC switches 31 to 33 and the collective DC switch 35. Here, the DC switches 31 to 33 have a junction box function capable of connecting or blocking DC power from the solar cell modules 11 to 15 in units of one string or two strings.

  The DC power stored in the input capacitor 3 is boosted by the booster circuit 4 and stored in the next-stage bus capacitor 5. The boosted voltage is controlled so as to have a voltage value suitable for the inverter circuit 7 in the next stage to convert it into alternating current. The step-up operation is performed by the step-up circuit 4 in response to a gate signal from the gate circuit 30 in accordance with a control command from the control circuit 20.

  The bus capacitor 5 has two capacitors connected in series. If the voltage balance of each capacitor is lost, the AC output from the inverter circuit 7 may be distorted, or the withstand voltage of each element may be exceeded. . Therefore, the power conditioner 1 is configured to balance the voltage of each capacitor by the balance circuit 6. The balance circuit 6 is controlled by the control circuit 20.

  The gate circuit 30 generates a gate signal based on a control command from the control circuit 20, and the inverter circuit 7 converts the DC power stored in the bus capacitor 5 into AC power based on the gate signal from the gate circuit 30. Is done. Since the stepped discontinuous component remains in the output of the inverter circuit 7, the output of the inverter circuit 7 is adjusted to a smooth sine wave by the filter circuit 8 at the next stage. After the noise is removed by the filter 9, the noise is input to the interconnection MC 51 and the independent MC 52.

  This sine wave output is connected to the power system via the connection MC 51 in the connection operation mode, and is consumed by, for example, a three-phase load in the facility. ) In addition, this sine wave output is supplied to a load connected to the self-supporting terminal block 54 via the self-supporting MC 52 in the self-supporting operation mode. Switching between the interconnection operation mode and the independent operation mode is executed by a user operation or automatically executed by the control circuit 20.

  Next, the configuration of the power supply circuit 10 will be described with reference to FIG. The power supply circuit 10 shown in FIG. 2 includes a power supply transformer 60 and a plurality of power supply circuit groups as main components. AC power obtained by switching AC power from the system power supply or DC power from the solar cell is input to the primary winding 67 of the power transformer 60.

  The power transformer 60 is provided with a plurality of secondary windings, and among these secondary windings, for example, the upper two secondary windings 61 and 62 in FIG. A winding for power source for driving the relay of the line, the interconnected MC 51 and the self-supporting MC 52, a power source winding for the display unit 40, and the like. Of these secondary windings, for example, the lower secondary winding 63 in FIG. 2 is a gate power supply winding.

  These secondary windings 61 to 63 are connected to a power supply circuit including a rectifier circuit, a smoothing circuit, and a regulator, respectively. For example, the secondary winding 63, which is a gate power supply winding, is connected to a first rectifier circuit 68 formed of a diode and a first smoothing circuit 69 formed of a capacitor. The first rectifier circuit 68 and the first smoothing circuit 69 function as a power conversion circuit (first power conversion circuit) that converts AC power from the secondary winding 63 of the power transformer 60 into DC power, In the following description, this power conversion circuit is referred to as a first gate power supply circuit 64.

  The output section 65 of the first gate power supply circuit 64 is provided with a switching circuit 71, and a plurality of pulse transformers 72-1 to 72-n are connected in parallel to the output side of the switching circuit 71. These pulse transformers 72-1 to 72-n are provided as many as the number of necessary gate power supplies, that is, the number corresponding to the switching elements constituting the booster circuit 4 and the inverter circuit 7 shown in FIG.

  On the secondary side of each of the pulse transformers 72-1 to 72-n, second rectifier circuits 73-1 to 73-n made of diodes and second smoothing circuits 74-1 to 74-1 made of capacitors are provided. 74-n is connected. The second rectifier circuits 73-1 to 73-n and the second smoothing circuits 74-1 to 74-n are power conversion circuits that convert AC power from the pulse transformers 72-1 to 72-n into DC power ( 2nd power converter circuit). In the following description, the switching circuit 71, the pulse transformers 72-1 to 72-n, the second rectifier circuits 73-1 to 73-n, and the second smoothing circuits 74-1 to 74-n This is referred to as a second gate power supply circuit 70.

  As described above, in the power supply circuit 10 according to the present embodiment, the switching circuit 71 is provided at the output portion 65 of one secondary winding 63 in the plurality of secondary windings provided in the power transformer 60. The switching circuit 71 is provided with a plurality of switching power supplies (gate power supplies).

  The switching circuit system may be a simple flyback system, a half-bridge system or a full-bridge system. However, if the full-bridge system is used, an efficient power supply is possible with a switching element having a low withstand voltage. Further, since the switching frequency is set to a high frequency of about 100 kHz, for example, a pulse transformer having a small size can be used.

  Next, the operation of the power supply circuit 10 will be described. The AC voltage applied to the primary side of the power transformer 60 is output to the secondary side as an AC voltage corresponding to the winding ratio between the primary side winding 67 and the secondary side winding 63, and the first rectifier circuit 68. Then, it is converted into a DC voltage through the first smoothing circuit 69. This DC voltage is converted to AC (pulsed) again by the switching circuit 71 and input to the primary side of each of the pulse transformers 72-1 to 72-n. On the secondary side of each of the pulse transformers 72-1 to 72-n, an AC voltage corresponding to the AC voltage applied to the primary side is generated, and these AC voltages are respectively supplied to the second rectifier circuits 73-1 to 73-73. -N is converted into a DC voltage through the second smoothing circuits 74-1 to 74-n.

  As described above, in the first gate power supply circuit 64 and the second gate power supply circuit 70, a DC power supply for driving the switching elements of the booster circuit 4 and the switching elements of the inverter circuit 7 is generated. The power is supplied to the gate circuit 30.

  Next, the effect of the power supply circuit 10 according to the present embodiment will be described with reference to FIG. In FIG. 3, as an example of a circuit board built in the power conditioner 1, for example, a power supply board 80 on which a first gate power supply circuit 64 is mounted, a second gate power supply circuit 70, and a gate circuit 30 are mounted. A gate substrate 81 and a power substrate 82 on which the booster circuit 4 and the inverter circuit 7 are mounted are shown.

  As described above, the first gate power supply circuit 64 includes one secondary winding 63 in the plurality of secondary windings, the first rectifier circuit 68 connected to the secondary winding 63, and The first smoothing circuit 69 is used. In the first gate power supply circuit 64, gate power supplies that drive the switching elements of the booster circuit 4 and the inverter circuit 7 are collectively generated.

  The power transformer of the prior art described in Patent Document 1 requires the number of secondary windings for the gate power circuit corresponding to the gate power circuit, and it is necessary to ensure the winding insulation performance. . Therefore, a certain size is required for the power transformer.

  In the embodiment of the present invention, since only one secondary winding for the gate power supply circuit is required, the type (number) of secondary windings of the power transformer 60 is reduced as compared with the prior art, and the power transformer 60 It is possible to reduce the size.

  In the embodiment of the present invention, the first gate power supply circuit 64 and the second gate power supply circuit 70 are electrically connected by a set of lead wires 66, and a direct current from the first gate power supply circuit 64 is obtained. A voltage is applied to the second gate power supply circuit 70. With this configuration, the power supply substrate 80 and the gate substrate 81 can be connected by only one set of lead wires 66, and the number of wirings can be reduced.

  In the embodiment of the present invention, since the gate circuit 30 and the second gate power supply circuit 70 that is highly related to the gate circuit 30 are mounted on one substrate, the gate substrate 81 can be easily manufactured. Thus, the cost can be reduced and the efficiency of inspection and maintenance can be improved.

  In the embodiment of the present invention, small pulse transformers 72-1 to 72-n are used for the second gate power supply circuit 70. By using the pulse transformers 72-1 to 72-n, The degree of freedom of the arrangement position of the second gate power supply circuit 70 can be increased.

  Further, when the power supply circuit according to the embodiment of the present invention is used for the power conditioner 1, a greater effect can be expected. Generally, in the power conditioner 1, since the booster circuit 4 and the inverter circuit 7 are essential, the number of gate power supply circuits required in these circuits increases, and accordingly, the power transformer 60 increases in size. . Therefore, it is necessary to secure a space for providing the power transformer 60 in the power conditioner 1, and it is necessary to relatively enlarge the casing of the power conditioner 1. According to the power supply circuit 10 according to the embodiment of the present invention, since the power transformer 60 can be reduced in size, the power transformer 60 can be provided in an empty space in the power conditioner 1. Can be miniaturized. In particular, when the multi-level chopper or the three-level inverter shown in this embodiment is adopted, the number of gates is large, and thus the above effect becomes more remarkable.

  The main circuit 90 of the power conditioner 1 of the photovoltaic power generation system is equipped with various sensors (a group of sensors that detect DC voltage, DC current, AC voltage, AC current, and the like). Detection data detected by these sensors is input to a control board (not shown), analyzed and calculated by a CPU in the control board, etc., for various control of the inverter (such as booster circuit control and inverter control). used. However, since these detection data have different potentials, they cannot be directly taken into the control board and must be isolated. That is, a circuit such as an isolation amplifier is required, and an independent power source for that purpose is required. In the power supply circuit 10 according to the present embodiment, these independent power supplies can be provided in a layout-free manner without increasing the power transformer 60 (without increasing the number of windings). In particular, the effect becomes more remarkable in the power conditioner 1 of the solar power generation system.

  In this embodiment, the power transformer 60 including three secondary windings 61, 62, and 63 is used as an example. However, the number of secondary windings of the power transformer 60 is limited to this. It is assumed that the power transformer 60 includes at least two secondary windings. Moreover, in this Embodiment, although the structural example which applied the power supply circuit 10 to the power conditioner 1 of a solar power generation system was demonstrated, the power supply circuit 10 is used for the power converter device etc. which used the self-extinguishing type switching element. Is also applicable.

  As described above, the power supply circuit 10 according to the present embodiment is a power supply circuit 10 that supplies at least gate power for driving a plurality of switching elements included in the main circuit 90, and includes a primary winding 67 and a plurality of power supplies. Power supply transformer 60 having the secondary side windings (61 to 63) and one secondary side winding 63 in each secondary side winding (61 to 63). A first power converter circuit (first rectifier circuit 68 and first smoothing circuit 69) for converting the AC power source from the line 63 into a DC power source, and switching for switching the DC power source from the first power converter circuit. A plurality of pulses connected in parallel to the output side of the circuit 71 and the switching circuit 71, and provided in a number corresponding to each of the switching elements, which insulates and outputs the high-frequency power converted by the switching circuit 71. The transformers 72-1 to 72-n are connected to the secondary sides of the pulse transformers 72-1 to 72-n, and the alternating current power from the pulse transformers 72-1 to 72-n is converted into direct current power. A plurality of second power conversion circuits (second rectifier circuits 73-1 to 73-n and second smoothing circuits 74-1 to 74-n) that output a DC power supply as the gate power supply. Since the configuration is such that only one secondary winding is required to obtain a gate power supply corresponding to the number of switching elements, the power transformer 60 can be reduced in size.

  The power conditioner 1 according to the present embodiment includes a power supply circuit 10, a plurality of switching elements driven by a gate power supply from the power supply circuit 10, a booster circuit 4 that boosts and outputs DC power, and a power supply An inverter circuit 7 having a plurality of switching elements driven by a gate power supply from the circuit 10 and converting DC power from the booster circuit 4 to AC power, and a gate circuit 30 for generating a gate signal of each switching element are provided. Since it did in this way, the power transformer 60 reduced in size can be provided in the empty space in the power conditioner 1, and size reduction of the power conditioner 1 can be achieved.

  Further, in the power conditioner 1 according to the present embodiment, the power supply circuit 10 performs isolation when the plurality of sensors (not shown) connected to the main circuit 90 are taken into the control board having different potentials. Since the power transformer 60 is used as a power source for the amplifier, the power transformer 60 can be provided as an independent power source for each sensor, and the power conditioner 1 can be downsized.

  In the power conditioner 1 according to the present embodiment, the power transformer 60 and the first power converter circuit are mounted on the power board 80, the switching circuit 71, the pulse transformers 72-1 to 72-n, and the second power. Since the conversion circuit and the gate circuit 30 are configured to be mounted on a second substrate (gate substrate 81) different from the first substrate (power supply substrate 80), the gate circuit 30 and the second gate power supply The circuit 70 and the circuit board 70 are mounted on a single substrate, which facilitates the manufacture of the gate substrate 81, reduces costs, and improves the efficiency of inspection and maintenance.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention in the implementation stage. Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent requirements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the above embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and is described in the column of the effect of the invention. In the case where a certain effect can be obtained, a configuration from which this configuration requirement is deleted can be extracted as an invention. Furthermore, the constituent elements over different embodiments may be appropriately combined.

  As described above, the power conditioner and the control device thereof according to the present invention can be applied to the power supply circuit and the power conditioner, and are particularly useful as an invention capable of further reducing the size of the power transformer.

  DESCRIPTION OF SYMBOLS 1 Power conditioner, 2, 9 Noise filter, 3 Input capacitor, 4 Booster circuit, 5 Bus capacitor, 6 Balance circuit, 7 Inverter circuit, 8 Filter circuit, 10 Power supply circuit, 11, 12, 13, 14, 15 Solar cell Module, 20 Control circuit, 21, 22, 23, 24, 25 Input terminal block, 30 Gate circuit, 31, 32, 33 DC switch, 35 Collective DC switch, 40 Display unit, 41, 42, 43, 44, 45 Backflow prevention diode, 51 Linked MC, 52 Freestanding MC, 53 Linked terminal block, 54 Freestanding terminal block, 60 Power transformer, 61, 62, 63 Secondary winding, 64 First gate power circuit, 65 Output Part, 66 lead wire, 67 primary winding, 68 first rectifier circuit, 69 first smoothing circuit, 70 second gate power supply circuit , 71 switching circuit, 72-1, 72-2, 72-3, 72-4, 72-n pulse transformer, 73-1, 73-2, 73-3, 73-4, 73-n second rectification Circuit, 74-1, 74-2, 74-3, 74-4, 74-n Second smoothing circuit, 80 power supply substrate, 81 gate substrate, 82 power substrate, 90 main circuit, 100 solar power generation system.

Claims (4)

A power supply circuit for supplying at least a gate power supply for driving a plurality of switching elements included in a main circuit,
A power transformer having a primary winding and a plurality of secondary windings;
A first power conversion circuit which is connected to one secondary winding in each of the secondary windings and converts an AC power supply from the secondary winding to a DC power supply;
A switching circuit for switching a DC power source from the first power conversion circuit;
A plurality of pulse transformers connected in parallel to the output side of the switching circuit, and provided in a number corresponding to each switching element, and insulating and outputting high-frequency power converted by the switching circuit;
A plurality of second power conversion circuits connected to the secondary side of each of the pulse transformers, converting AC power from each of the pulse transformers to DC power, and outputting the DC power as the gate power;
A power supply circuit comprising: The power supply circuit according to claim 1;
A booster circuit having a plurality of switching elements driven by a gate power supply from the power supply circuit and boosting and outputting DC power;
An inverter circuit having a plurality of switching elements driven by a gate power supply from the power supply circuit, and converting DC power from the booster circuit to AC power;
A gate circuit for generating a gate signal of each switching element;
Power conditioner with   The power conditioner according to claim 2, wherein the power supply circuit is used as a circuit power supply for a plurality of sensors connected to the main circuit. The power transformer and the first power conversion circuit are mounted on a first substrate,
The switching circuit, the pulse transformers, the second power conversion circuits, and the gate circuit are mounted on a second substrate different from the first substrate. The power conditioner described in 3.

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