JP4702141B2 - Power converter - Google Patents

Description

  The present invention relates to a power conversion device such as a solar power generation system or a small fuel cell power generation system that handles a relatively large current.

  In a small solar power generation system or a small fuel cell power generation system for a house, the rating of the inverter device used for power conversion is about 1 to 5 kW, and an example of such an inverter device is shown in FIG.

  FIG. 9 shows a schematic circuit configuration of a conventional inverter device. The inverter device 100 includes a boosting unit 200 that boosts an input voltage, and a sine wave generation unit 300 that converts the voltage boosted by the boosting unit 200 from DC to AC and outputs the converted voltage. The circuit configuration is as follows.

  The step-up circuit B1 constituting the step-up unit 200 includes a push-pull inverter circuit 4a including a pair of switch elements Q1 and Q2 controlled by a control unit (not shown), a smoothing capacitor C1, and a step-up circuit. The secondary side circuit includes a rectifier circuit D1 including a plurality of diodes, a choke coil L1, and a smoothing circuit including smoothing capacitors C3 and C5.

  The sine wave generation unit 300 includes an inverter circuit 5 that converts an input voltage from the boosting unit 200 into an AC voltage, and a filter circuit 6 that smoothes the output of the inverter circuit 5 and converts the output waveform into a sine wave waveform. . The inverter circuit 5 is configured by full-bridge connection of switching elements Q5, Q6, Q7, and Q8 such as IGBTs, and power conversion is performed by controlling on / off of each switching element Q5, Q6, Q7, and Q8 by a control unit. I do. The filter circuit 6 includes a reactor L3 having one end connected to the connection point of the switch elements Q5 and Q7 connected in series, a reactor L4 having one end connected to the connection point of the switch elements Q6 and Q8 connected in series, It comprises a low-pass filter composed of a capacitor C6 connected between the other ends of the reactors L3 and L4, and smoothes the ripple component by the switching operation of the inverter circuit 5.

  By the way, when the input voltage to the inverter device is relatively low due to the type and configuration specifications of a power generation system such as a photovoltaic power generation system or a small fuel cell power generation system that is a power supply source, In order to convert the input voltage to a high voltage, it is common to use an inverter device provided with the booster circuit B1 as exemplified above. However, like this inverter device, a single booster circuit, a single boost transformer If a high step-up ratio is to be obtained, a large difference occurs in the wire diameter and the number of turns of the primary and secondary windings of the step-up transformer, and it is very difficult to construct a step-up transformer with a high degree of coupling. .

  Therefore, in such a configuration, a step-up transformer having a low degree of coupling is used, which causes problems such as a reduction in power conversion efficiency and generation of a surge voltage to the switch element during switching. In order to solve the above problem in the circuit configuration of the boosting unit, as shown in FIG. 1, a plurality of boosting circuits are provided in parallel in the boosting unit, and the input voltage is distributed and shared by the boosting transformers of the boosting circuits. There is a technique for making the windings of the step-up transformer uniform, obtaining a high degree of coupling, and suppressing a reduction in power conversion efficiency, generation of a surge voltage, and the like.

In addition, in order to suppress surge voltage and reduce wiring impedance in a boosting unit or the like of an inverter device, a structure and configuration such as a bus bar in which capacitors are connected in series and parallel have been proposed. (For example, refer to Patent Documents 1 and 2).
JP 2003-319665 A JP 11-055938 A

  However, in the circuit configuration of the primary circuit in which a plurality of boosting circuits are provided in the boosting unit, each component is arbitrarily arranged on the printed circuit board, or each boosting circuit is connected by an electric wire. Therefore, the effect of suppressing the surge voltage of the capacitor is hindered by the copper foil pattern on the printed circuit board and the wiring impedance due to the connecting wire between the circuits, resulting in excessive stress on the switch element. There was a problem.

  In order to suppress such a surge voltage, in Patent Document 1, wiring inductance is reduced by arranging a pair of bus bars (bus bars) connected in parallel to a plurality of capacitors so as to face each other in parallel. Further, in Patent Document 2, when a large number of capacitors are connected in parallel, the capacitors are arranged in a U-shape, and the cross-sectional shape of the bus bar is set to an L shape, etc., to ensure the distance between the bus bars and between the positive and negative electrodes. The balance of wiring inductance is maintained to reduce current imbalance.

  However, in connection with the arrangement of components such as elements and wiring in the booster circuit, the wiring length between the components is imbalanced due to restrictions on the arrangement of components, and power is evenly distributed to each booster circuit. In addition to the above restrictions on the switch elements and capacitor arrangement for suppressing the surge voltage, the primary side booster circuit that comprehensively satisfies the restrictions on the combined arrangement and wiring, etc. It was difficult to make the arrangement configuration.

  The present invention has been made in view of the above points, and in a power conversion device in which the inputs of primary circuits of each of a plurality of booster circuits are connected in parallel, the step-up transformer and smoothing that constitute the plurality of booster circuits. Capacitor and switch element can be connected so that power is evenly supplied through the shortest path, and the surge voltage of the switch element is suppressed to provide a highly efficient power converter with little loss and electromagnetic noise The purpose is to do.

In order to achieve the above object, the invention of claim 1 is characterized in that an input part of a primary side circuit of each of a plurality of booster circuits for converting a large current / low voltage input into a small current / high voltage output is connected in parallel, In the power conversion device in which the outputs of the secondary side circuits of each of the plurality of booster circuits are connected in series, the power supply terminals of the primary side circuit of the booster circuit are a pair of parallel and horizontal conductor plates The plurality of booster circuits are sequentially arranged in a line, and the power supply terminals of the respective primary side circuits are arranged on the pair of conductor plates, and power is supplied from the outside. The positive and negative power supply sections are provided on the pair of conductor plates, and a plurality of capacitors are connected in parallel to the pair of conductor plates .

A second aspect of the present invention, in the power conversion device according to claim 1, wherein the power supply portion of the positive electrode and the negative electrode, and a mutually Rukoto provided at one end on the opposite side of the pair of conductor plates .

A third aspect of the present invention, in the power converter according to claim 1 or claim 2, and Rukoto insulating sheet provided between said the positive electrode side conductor plate the condenser outer shell case did.

  According to a fourth aspect of the present invention, in the power conversion device according to any one of the first to third aspects, the one of the pair of conductor plates has a predetermined step with respect to the other of the conductor plates. It was decided to provide it.

  According to the first aspect of the present invention, when the input parts of the primary side circuits of the plurality of booster circuits are connected in parallel, the power supply terminal of the primary circuit of the booster circuit is constituted by the pair of conductor plates. For example, the smoothing capacitor and the switch element of the primary side circuit can be connected with a low impedance at the shortest distance. For this reason, it is possible to suppress the surge voltage of the switch element and to suppress loss and electromagnetic noise that occur during switching.

  According to the second aspect of the present invention, since the power supply from the outside to each conductor plate is supplied from one end opposite to each other, each booster circuit connected to the power supply terminal on the conductor plate is supplied. Therefore, it is possible to avoid the risk that the power distribution of the booster circuits becomes even and the burden on some booster circuits increases, resulting in destruction of the booster circuit beyond the device withstand capability.

  According to the invention of claim 3, since the insulation between the outer shell of the capacitor and the charging part can be ensured by the insulating sheet, safety against a short circuit or the like can be ensured.

  According to the invention of claim 4, since the terminals of the two electrodes of the capacitor are connected to the power supply terminals of the respective conductor plates at different heights, the insulation distance between the terminals of the two electrodes of the capacitor and between the conductor plates. Can be ensured, and safety against short circuits and the like can be improved.

  Hereinafter, an inverter device as a power conversion device according to an embodiment of the present invention will be described with reference to FIGS. 1 to 8.

  First, the circuit configuration of the inverter device 1 of the present embodiment will be described with reference to FIG. FIG. 1 shows a schematic circuit configuration of an inverter device 1 according to the present embodiment. The inverter device 1 includes as main components a booster 2 that boosts an input voltage and a sine wave generator 3 that converts an output of the booster 2 into an AC voltage. The step-up unit 2 includes two step-up circuits B1 and B2 having push-pull inverter circuits 4a and 4b having the same configuration as that described with reference to FIG. 9, and is input to the primary side circuit of the step-up circuits B1 and B2. Primary side positive terminals (c, h) of the step-up transformers T1, T2, which are parts, smoothing capacitors C1, C2, and terminals of the switching elements Q1, Q2, Q3, Q4 (a, b, f, g and d, e, i, j) are connected in parallel to the respective power supply terminals provided on the conductor plates BUS (+) and BUS (−) that receive the supply of power from the outside, and at the output part of the secondary side circuit The terminals of each pole of a certain smoothing capacitor C3, C4 are connected in series. The sine wave generation unit 3 has the same configuration as that described with reference to FIG. 9, and converts the voltage supplied from the boosting unit 2 into an AC voltage by the inverter circuit 5, and further a ripple component by the subsequent filter circuit 6. Is supposed to be smoothed.

  The power conversion by the inverter device 1 is performed as follows. First, large current and low voltage DC power supplied from a photovoltaic power generation system or the like (not shown) is supplied to the primary side input section of each booster circuit B1, B2 connected in parallel. In each booster circuit B1, B2, the supplied DC voltage is smoothed by the smoothing capacitors C1, C2, respectively, and then a pair of switching elements Q1, Q2, and Q3 of the push-pull inverter circuits 4a, 4b, The voltage is boosted by step-up transformers T1 and T2 driven by Q4, and is rectified and smoothed by a smoothing circuit including rectifier circuits D1 and D2 and choke coils L1 and L2 and smoothing capacitors C3 and C4 on the secondary side, and is output. The Since the output sections of the secondary side circuits of the respective booster circuits B1 and B2 are connected in series, the output voltages are added together, and the further increased DC voltage (DC350V) is smoothed by the smoothing capacitor C5. And supplied to the sine wave generator 3. In the sine wave generating unit 3, the switching elements Q5, Q6, Q7, and Q8 constituting the inverter circuit 5 are switched according to PWM control or the like of the control unit, and the DC voltage supplied from the boosting unit 2 is converted into a sinusoidal AC voltage. Convert to and output. Then, the filter circuit 6 smoothes the ripple component and outputs the converted AC voltage (AC 200 V).

  Next, a specific configuration of the primary side circuits of the booster circuits B1 and B2 will be described with reference to FIGS. FIG. 2 shows a specific structure of the primary side circuit of the booster circuits B1 and B2 constituting the booster unit 2 of the inverter device 1 according to the embodiment of the present invention. FIG. 3 shows the structure of the disassembled state of the primary circuit. FIG. 4 shows a planar arrangement of the primary circuit. FIG. 5 shows a planar arrangement with the smoothing capacitors C1 and C2 removed in the primary circuit. 6 and 7 show a planar arrangement and a perspective configuration in a state where the positive and negative conductor plates are removed from the primary circuit. FIGS. 8A and 8B show schematic configurations of the primary circuit as viewed from the side.

  In these drawings, the primary side circuit includes step-up transformers T1 and T2 provided on the heat sink 7 and a power supply terminal and a power supply provided on a metal-based printed circuit board 8 on the heat sink 7. And a pair of positive electrode side conductor plates BUS (+) (hereinafter referred to as positive electrode bus bars) and a negative electrode side conductor plate BUS (−) (hereinafter referred to as negative electrode bus bars). 4 pieces of smoothing capacitors C1, C2, insulating sheet 9, positive and negative bus bars BUS (+), BUS (-) to four printed circuit boards 10a, 10b, 11a, 11b and switch elements Q1, Q2, Q3, and Q4.

  On the heat radiating plate 7, the step-up transformers T1 and T2 of the step-up circuits B1 and B2 are juxtaposed in parallel. A printed circuit board 8 is fixed to the. On the printed circuit board 8, two pairs of switch elements Q1, Q2, Q3, and Q4 are provided on the rear side, which is the step-up transformers T1 and T2, and provided on the primary side of each step-up transformer T1 and T2. Two negative terminals T1a, T1b and T2a, T2b are connected to the respective output terminals Q1a, Q2a, Q3a, and Q4a of the switching elements Q1, Q2 and Q3, Q4 by soldering.

  Above the switch elements Q1, Q2, Q3, and Q4, a positive bus bar BUS (+) and a negative bus bar BUS (-) are arranged in parallel and horizontally in this order from the step-up transformer side so as to cover these switch elements. Has been. The positive and negative busbars BUS (+) and BUS (−) are made of the same material having the same thickness, such as a conductive metal plate such as copper, and the switch elements Q1, Q2, Q3, and Q4 are arranged in a line ( Hereinafter, it has rectangular terminal surfaces 12 and 13 having a long side in the circuit width direction). In addition, the width | variety and length of the terminal surfaces 12 and 13 of a positive electrode and negative electrode bus bar BUS (+) and BUS (-) are substantially the same.

  On the terminal surface 12 of the positive bus bar BUS (+) (shown virtually by a broken line frame in FIG. 4), as shown in FIGS. 4 and 5, two projections 14a are provided on the front side as power supply terminals. , 14b (collectively referred to as the protrusion 14) and four small holes 15a, 15b, 15c, 15d (collectively referred to as the small holes 15) on the rear side and parallel to the circuit width direction, respectively. Are provided at predetermined intervals in a straight line. These protrusions 14 and small holes 15 have positive electrode terminals T1c and T2c on the primary side of the step-up transformers T1 and T2 and two sets of smoothing capacitors C1 and C2 provided on the upper side as input portions on the positive electrode side. One end of each terminal is connected by soldering via the insulating sheet 9. Further, fixing holes 16a and 16b are provided at both ends of the terminal surface 12 in the circuit width direction, and these are engaged with the support posts 10a and 10b fixed to the printed circuit board 8, respectively. The bus bar BUS (+) is fixed to the printed circuit board 8. A positive power supply unit 17 formed by bending or the like of the end of the positive bus bar BUS (+) is provided above the vicinity of the fixing hole 16a of the terminal surface 12.

  As shown in FIGS. 4 to 6, the terminal surface 13 of the negative bus bar BUS (−) (shown virtually by a broken line frame in FIG. 4) has four small holes 18 a on the front stage side as power supply terminals. , 18b, 18c, 18d (collectively referred to as small holes 18), four rear projections 19a (shown in FIG. 2), 19b, 19c, 19d (collectively referred to as projection 19) Are arranged in parallel with each other in the circuit width direction at a predetermined interval. The other end of the terminals of the four smoothing capacitors C1 and C2 provided in the upper portion is connected to the small hole 18, and the protrusion 19 is connected to the input terminals of the switch elements Q1, Q2, Q3, and Q4 from the lower surface by soldering. The auxiliary terminals 20a, 20b, 20c, and 20d are connected by soldering as input portions on the negative electrode side. Further, fixing holes 21 a and 21 b are provided at both ends of the terminal surface 13 in the circuit width direction, and these engage with the support pillars 11 a and 11 b fixed to the printed circuit board 8. BUS (−) is fixed to the printed circuit board 8. A negative electrode power supply unit 22 formed by bending the end of the negative electrode bus bar BUS (−) or the like is provided above the vicinity of the fixing hole 21 b of the terminal surface 13. The capacitors C1 and C2 are connected by soldering to the small hole 15 of the positive bus bar BUS (+) and the small hole 18 of the negative electrode bus bar BUS (−) as described above, so that the positive and negative bus bars BUS (+) are connected. , BUS (-).

  As shown in FIGS. 4 to 6, smoothing capacitors C1 and C2, step-up transformers T1 and T2, and step-up transformers T1 and T2, which are arranged in a straight line parallel to the circuit width direction on the heat sink 7 or the printed circuit board 8, respectively. Q4 and the respective terminals are arranged so as to be symmetric with respect to a center line 23 passing through an intermediate point on the heat sink 7 of the step-up transformers T1 and T2 and orthogonal to the circuit width direction. Accordingly, the power supply terminals provided on the terminal surfaces 12 and 13 of the positive and negative busbars BUS (+) and BUS (−) connected to these have the same arrangement configuration. As shown in FIG. 5, the insulating sheet 9 is a rectangular sheet having substantially the same width as the positive bus bar BUS (+), and the same number of holes are provided at the same position as the small holes 15. The smoothing capacitors C1 and C2 are arranged in a shape so that the lower surface of the outer shell case can be accommodated.

  Further, as shown in FIG. 8A, the columns 10a and 10b that support the positive bus bar BUS (+) are configured to be lower than the columns 11a and 11b that support the negative electrode bus BUS (−). The terminal surface 12 of BUS (+) is disposed at a lower position than the terminal surface 13 of the negative bus bar (−), and has a step between the terminal surfaces 12 and 13.

  Further, as another configuration in which a step is provided between the terminal surfaces 12 and 13, as shown in FIG. 8B, the length of the short side direction of the insulating sheet 9 is extended in the direction of the negative bus bar BUS (−), and the positive electrode On the bus bar BUS (+) side, the columns 10a and 10b, the positive bus bar BUS (+), and the insulating sheet 9 are arranged in this order from the printed circuit board 8 side. On the negative bus bar BUS (−) side, the columns 11a and 11b and the insulating sheet 9 are arranged. The thickness of the insulating sheet 9 while using the same struts without changing the lengths of the struts 10a and 10b and the struts 11a and 11b by stacking and forming the negative bus bar BUS (-) in this order. It is also possible to provide a step between the terminal surfaces 12 and 13 of the positive bus bar BUS (+) and the negative bus bar BUS (−).

  As described above, by configuring the primary side circuit of the booster unit 2 of the inverter device 1, when the input units of the primary side circuits of the booster circuits B 1 and B 2 are connected in parallel, the positive busbar BUS (+) and Since the smoothing capacitors C1 and C2 and the terminals of the switch elements Q1 to Q4 are connected in the shortest distance by the respective power supply terminals provided in the negative bus bar BUS (-), the connection between them is a low impedance connection, and the switch elements Q1 to Q4 are connected. It is possible to reduce the surge voltage and the electromagnetic noise generated during switching. Further, since the plurality of switch elements Q1 to Q4 are individually connected to the negative electrode bus bar BUS (−) with connection points, the impedance can be lowered.

Also, the positive electrode power supply part 17 and the negative power supply unit 22 receives power from the outside, positive electrode bus bar BUS (+) and negative bus bar BUS (-) because it is provided at one end on the opposite sides of the positive electrode The power distribution to each booster circuit B1, B2 connected to each power supply terminal on the bus bus BUS (+) and the negative bus bus BUS (-) becomes even, the burden on one booster circuit increases, It is possible to avoid a risk of exceeding the element withstand capability of the booster circuit and leading to destruction.

  Further, since the insulating sheet 9 is provided between the terminal surface 12 of the positive bus bar BUS (+) and the smoothing capacitors C1 and C2, insulation between the outer shells of the smoothing capacitors C1 and C2 and the charging part can be secured. It is possible to ensure safety against short circuits.

  Further, the terminals of both electrodes of the smoothing capacitors C1 and C2 are connected to the respective power supply terminals provided on the terminal surfaces 12 and 13 of the positive bus bar BUS (+) and the negative bus bar BUS (−) at different heights. Insulation distances between the terminals of the smoothing capacitors C1 and C2 and between the positive bus bar BUS (+) and the negative bus bar BUS (−) can be ensured, and safety against short circuits and the like can be improved.

  Moreover, the positive electrode bus bar BUS (+) and the negative electrode bus bar BUS (−) which are a pair of conductor plates are horizontally arranged in a state of being floated above the printed circuit board 8 by the columns 10 a, 10 b, 11 a, 11 b, The capacitors C1 and C2 are supported between the pair of conductor plates, and the switch elements Q1 to Q4 are disposed in the space below the capacitors C1 and C2, so that the space is effectively utilized.

  Further, the conductor plate and the switch elements Q1 to Q4 are connected by soldering the protruding portions 19a to 19d protruding from the conductor plate and auxiliary terminals 20a to 20d that are separately interposed. As described above, the connection position of each terminal is shifted from directly below the capacitors C1 and C2, thereby facilitating connection work during assembly.

  In addition, this invention is not restricted to the structure of the said various embodiment, A various deformation | transformation is possible in the range which does not change the meaning of invention.

The circuit diagram of the inverter apparatus which concerns on embodiment of this invention. The perspective view of the primary side circuit which comprises the pressure | voltage rise part in an apparatus same as the above. The perspective view of the decomposition | disassembly state of a circuit same as the above. The top view in a circuit same as the above. The top view of the state which removed the smoothing capacitors C1 and C2 in a circuit same as the above. The top view of the state which removed the positive and negative side conductor board in a circuit same as the above. The perspective view of the state which removed the positive and negative side conductor board in a circuit same as the above. (A), (b) is a side view of a circuit same as the above, respectively. The circuit diagram of the conventional inverter apparatus.

Explanation of symbols

1 Inverter device (power converter)
2 Booster 3 Sine wave generator 7 Heat sink 8 Printed circuit board 9 Insulating sheet 10a, 10b Post 11a, 11b Post 14a, 14b Protrusion (power supply terminal)
15a, 15b, 15c, 15d Small hole (power supply terminal)
17 Positive power supply unit 18a, 18b, 18c, 18d Small hole (power supply terminal)
19a, 19b, 19c, 19d Protrusion (power supply terminal)
22 Negative power supply part a thru | or j terminal (input part)
B1, B2 Booster circuit C1, C2 Capacitor BUS (+) Positive busbar (conductor plate)
BUS (-) Negative bus bar (conductor plate)

Claims (4)

The input part of each primary side circuit of the plurality of booster circuits for converting the large current and low voltage input into the small current and high voltage output is connected in parallel, and the output part of the secondary side circuit of each of the plurality of booster circuits Are connected in series,
The power supply terminal of the primary side circuit of the booster circuit is composed of a pair of parallel and horizontal conductor plates,
The plurality of booster circuits are sequentially arranged in a row, and the power supply terminals of the respective primary side circuits are disposed on the pair of conductor plates ,
The positive and negative power supply portions to which power is supplied from the outside are provided on the pair of conductor plates,
A power converter , wherein a plurality of capacitors are connected in parallel to the pair of conductor plates . The power converter according to claim 1, wherein the positive and negative power supply units are provided at one end of the pair of conductor plates opposite to each other. The power conversion device according to claim 1, wherein an insulating sheet is provided between the positive electrode conductor plate and the outer shell case of the capacitor.   4. The power converter according to claim 1, wherein one of the pair of conductor plates is provided with a predetermined step with respect to the other of the conductor plates. 5. .