JP5516623B2 - Power converter - Google Patents

Description

  The present invention relates to a power converter, and is particularly suitable for application to a semiconductor device mounting method used in a power converter.

Conduction / radiation noise is generated from semiconductor power conversion devices such as inverters, and electronic equipment manufacturers need to manufacture and sell products that comply with the standard of conduction / radiation noise.
FIG. 7 is a diagram illustrating an example of a semiconductor power conversion device using an inverter.
In FIG. 7, a three-phase AC power source 101 is connected to an inverter 103 via a rectifier 102 and a smoothing capacitor C <b> 4, and the inverter 103 is connected to a motor 104. Each phase of the three-phase AC power supply 101 is grounded through grounding capacitors C1 to C3 in order to reduce common mode noise. Here, the rectifier 102 is provided with rectifier diodes D1 to D6, and the inverter 103 is provided with switching elements M11 to M16 and feedback diodes D11 to D16 connected in reverse parallel to the switching elements M11 to M16, respectively. Yes.

For example, IGBTs (Insulated Gate Bipolar Transistors) can be used as the switching elements M11 to M16.
The AC voltage generated by the three-phase AC power source 101 is converted into a DC voltage by the rectifier 102 and the smoothing capacitor C4, and the DC voltage generated by the rectifier 102 and the smoothing capacitor C4 is converted into an AC voltage by the inverter 103. It is converted and supplied to the motor 104.

Here, a basic circuit (arm) is configured by a set of the switching elements M11 to M16 and the feedback diodes D11 to D16, and the inverter 103 can be configured by using six of the basic circuits.
The inverter module is installed on a heat sink 105 for cooling, and the heat sink 105 is generally connected to a ground potential for safety.

  In addition to the discrete configuration of the IGBT, the inverter module can be configured as one set (2 in 1 type) for the upper and lower arms 2 elements, or as one set (6 in 1 type) for 6 elements, In a three-phase inverter, in addition to a method of connecting discretely configured IGBTs in two series-three parallel connections, a set of two elements can be connected in three parallel or a set of six elements can be used as they are.

FIG. 8 is a perspective view showing an external configuration of a discrete IGBT.
In FIG. 8, the IGBT 111 is sealed with a sealing resin, and the gate terminal 111a of the IGBT 111, the collector terminal 111b connected to the positive output terminal, and the emitter terminal 111c connected to the negative output terminal are taken out from the sealing resin. It is.

FIG. 9 is a perspective view showing a conventional IGBT mounting method, and FIG. 10 is a cross-sectional view showing a conventional IGBT mounting method.
9 and 10, when an inverter is constituted by the IGBT 111, the IGBT 111 is screwed to a heat sink 123 connected to the ground potential for heat dissipation. For example, in a three-phase inverter, three IGBTs 111 for the upper arm and three IGBTs 111 for the lower arm can be screwed to the same heat sink 123 as a set.
The IGBT 111 screwed to the heat sink 123 is mounted on the printed circuit board 121 on which the printed pattern 122 is formed, and the gate terminal 111a, the collector terminal 111b, and the emitter terminal 111c are connected to the printed pattern 122.

  Here, in order to connect the semiconductor chip constituting the IGBT 111 to the output terminal, the semiconductor chip is mounted on the metal pattern inside the package of the IGBT 111. When the IGBT 111 is mounted on the heat sink 123, the metal pattern inside the package of the IGBT 111 and the heat sink 123 are disposed so as to face each other, so that the stray capacitance C122 is formed between the collector of the IGBT 111 and the heat sink 123. .

  Further, when the IGBT 111 screwed to the heat sink 123 is mounted on the printed circuit board 121, the printed pattern 122 and the heat sink 123 are disposed so as to face each other, so that the electrostatic coupling between the printed pattern 122 and the heat sink 123 is performed. As a result, the stray capacitance C 121 is formed, and when the print patterns 122 are arranged close to each other, stray capacitance is also formed between the print patterns 122.

  That is, for the sake of simplicity, when considering only the electrostatic coupling around the IGBT 111, the printed pattern 122 that connects the positive electrode of the DC intermediate capacitor and the collector of the IGBT 111 for the upper arm is the pattern A, and the emitter of the IGBT 111 for the upper arm. Print pattern 122 connecting the collector of IGBT 111 for the lower arm and pattern C, and pattern C connecting the emitter of the lower arm IGBT 111 and the negative electrode of the DC intermediate capacitor are printed patterns A, B, C And the heat sink 123, stray capacitance is formed by electrostatic coupling between the print patterns A and B, between the print patterns B and C, and between the print patterns A and C.

FIG. 11 is a diagram showing a common mode current path when the inverter having the two-element configuration of FIG. 7 is used.
In FIG. 11, the inverter module is mounted on a heat sink 105 having the same potential as the ground potential, and has a stray capacitance C5 formed between the upper arm side collector and the heat sink 105 and between the lower arm side collector and the heat sink 105, C6 is also connected to ground potential. The charge / discharge currents of these stray capacitances C5 and C6 become a common mode current, and this common mode current mainly flows through a common mode current path RC passing through the stray capacitances C5 and C6. Similarly, the charge / discharge current of the stray capacitance C121 between the print pattern 122 and the heat sink 123 becomes a common mode current.

The magnitude of conduction noise and radiation noise depends on the magnitude of the common mode current, and the magnitude of the common mode current is proportional to the stray capacitance between the upper and lower arm connection point and the ground. As the stray capacitance between the ground and the ground increases, the conduction noise and radiation noise also increase.
Patent Document 1 discloses that unnecessary electromagnetic waves generated by charging / discharging current flowing from the power conversion circuit through the stray capacitance can be suppressed to a low level by reducing the area of the current loop in the semiconductor module of the power conversion circuit. In addition to the output electrode connected to the DC positive potential output, the DC negative potential output electrode, and the load on the semiconductor module constituting the power conversion circuit, the output electrode having the same potential as the ground potential, etc. And a method of connecting it to a copper base having the same potential as the ground potential via a copper bar is disclosed.

JP 2004-7888 A

However, in the conventional IGBT 111 mounting method, the printed pattern 122 and the heat sink 123 are arranged to face each other. For this reason, the stray capacitance C121 between the printed pattern 122 and the heat sink 123 increases and the common mode current increases, which causes a problem of increasing conduction noise and radiation noise.
In the method disclosed in Patent Document 1, the common mode current path can be reduced. However, since the stray capacitance C121 between the printed pattern 122 and the heat sink 123 is not considered, the common mode current is large. There was a problem that the thickness could not be reduced.
Accordingly, an object of the present invention is to provide a power conversion device capable of suppressing an increase in common mode current caused by a layout when a semiconductor switching element is mounted.

In order to solve the above-described problem, according to the power conversion device of claim 1, a semiconductor switching element that performs a switching operation, a printed board on which the semiconductor switching element is mounted on a surface side, and a surface of the printed board And a conductor that dissipates heat generated from the semiconductor switching element, and a first conductor that is formed on the surface side of the printed circuit board and that is connected to a terminal whose potential does not vary during the switching operation of the semiconductor switching element. A printed pattern, and a second printed pattern formed on the back side of the printed circuit board and connected to a terminal whose potential is changed by a switching operation of the semiconductor switching element. The second printed pattern and the conductor placing the first printed pattern such areas bets overlap is covered And features.

  As a result, even when the printed pattern and the conductor are arranged to overlap, the stray capacitance formed between the printed pattern and the conductor can be reduced. For this reason, it is possible to suppress an increase in common mode current due to the layout at the time of mounting the semiconductor switching element while suppressing an increase in mounting area, and it is possible to reduce conduction noise and radiation noise.

In addition , the lines of electric force reaching the conductor from the second print pattern can be shielded by the first print pattern, and even when the second print pattern and the conductor are arranged in an overlapping manner, Since the stray capacitance formed between the conductors can be reduced, the increase in the common mode current due to the layout when mounting the semiconductor switching element is suppressed while the increase in the mounting area is suppressed. It becomes possible.

Further, according to the power converter according to claim 2, wherein the first printed pattern and the conductive region and overlap the body, characterized in that a larger area than the region with the second printed pattern and the conductor overlap And
As a result, the lines of electric force reaching the conductor from the second print pattern can be reduced, and the stray capacitance formed between the second print pattern and the conductor can be reduced. It is possible to suppress an increase in common mode current due to the layout when the switching element is mounted.

  According to the power conversion device of the present invention, it is possible to reduce the stray capacitance formed between the printed pattern and the conductor, and to increase the common mode current due to the layout when the semiconductor switching element is mounted. Since it becomes possible to suppress, conduction noise and radiation noise can be reduced.

It is sectional drawing which shows the mounting method of IGBT of the power converter device which concerns on 1st Embodiment relevant to this invention. It is sectional drawing which shows the mounting method of IGBT of the power converter device which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows the mounting method of IGBT of the power converter device which concerns on 3rd Embodiment of this invention. It is sectional drawing which shows the mounting method of IGBT of the power converter device which concerns on 4th Embodiment of this invention. It is sectional drawing which shows the mounting method of IGBT of the power converter device which concerns on 5th Embodiment of this invention. It is a figure which shows in schematic form the schematic structure of the power converter device which concerns on 6th Embodiment of this invention. It is a figure which shows an example of the semiconductor power converter device which used the inverter. It is a perspective view which shows the external appearance structure of IGBT of a discrete structure. It is a perspective view which shows the mounting method of the conventional IGBT. It is sectional drawing which shows the mounting method of the conventional IGBT. It is a figure which shows the common mode electric current path | route in the case of using the inverter of 2 element structure of FIG.

Hereinafter, a power converter according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing a method for mounting an IGBT of a power converter according to a first embodiment related to the present invention.
In FIG. 1, the IGBT 14 is screwed to a heat sink 13 connected to the ground potential for heat dissipation. For example, in a three-phase inverter, three IGBTs 14 for the upper arm and three IGBTs 14 for the lower arm can be screwed to the same heat sink 13 as a set.

The IGBT 14 screwed to the heat sink 13 is mounted on the printed circuit board 11 on which the printed pattern 12 is formed, and the gate terminal, collector terminal, and emitter terminal of the IGBT 14 are connected to the printed pattern 12.
Here, the heat sink 13 can be disposed at a position that does not face the printed pattern 12 connected to a terminal whose potential varies in the switching operation of the IGBT 14. For example, when a three-phase inverter is configured using the IGBT 14, the print pattern 12 connected to the upper and lower arm connection points can be disposed at a position not facing the heat sink 13.

  As a result, the printed pattern 12 and the heat sink 13 can be arranged apart from each other, and the capacitance of the capacitor is proportional to the electrode area and relative dielectric constant and inversely proportional to the distance between the electrodes. Accordingly, the stray capacitance C11 formed between the capacitor 13 and the capacitor 13 can be reduced. For this reason, it becomes possible to suppress the increase in the common mode current resulting from the layout when the IGBT 14 is mounted, and it is possible to reduce conduction noise and radiation noise.

FIG. 2 is a cross-sectional view illustrating a method for mounting an IGBT of a power conversion device according to a second embodiment of the present invention.
In FIG. 2, the IGBT 24 is screwed to a heat sink 23 connected to the ground potential for heat dissipation. For example, in a three-phase inverter, three IGBTs 24 for the upper arm and three IGBTs 24 for the lower arm can be screwed to the same heat sink 23 as a set.

  A printed pattern 22b is formed on the front surface of the printed circuit board 21, and a printed pattern 22a is formed on the back surface of the printed circuit board 21 so as to face the printed pattern 22b. The IGBT 24 screwed to the heat sink 23 is mounted on the surface side of the printed circuit board 21, and a terminal whose potential does not vary by the switching operation of the IGBT 24 is connected to the printed pattern 22 b, and the potential is switched by the switching operation of the IGBT 24. The terminal where is fluctuated is connected to the print pattern 22a. In addition, as a method of connecting the terminal whose potential fluctuates by the switching operation of the IGBT 24 to the printed pattern 22a, for example, it can be performed through a through hole formed in the printed board 21.

  For example, when a three-phase inverter is configured using the IGBT 24, the terminals that become the upper and lower arm connection points may be connected to the printed pattern 22a, and the terminals connected to the positive and negative electrodes of the power converter may be connected to the printed pattern 22b. it can. Here, even when a stray capacitance is formed between the print pattern 22b and the heat sink 23, the common mode current does not flow because the potential does not fluctuate due to the switching operation of the IGBT 24. On the other hand, by forming the print pattern 22b so as to face the print pattern 22a, the electrostatic coupling between the print patterns 22a and 22b can be strengthened, and the electric lines of force reaching the heat sink 23 from the print pattern 22a are printed. It can be shielded by the pattern 22b.

  Thereby, even when the printed pattern 22a and the heat sink 23 are arranged so as to overlap with each other, the stray capacitance C21 formed between the printed pattern 22a and the heat sink 23 can be reduced, thereby increasing the mounting area. It is possible to suppress an increase in common mode current due to the layout when the IGBT 24 is mounted, and to reduce conduction noise and radiation noise.

FIG. 3 is a cross-sectional view illustrating a method for mounting an IGBT of a power conversion device according to a third embodiment of the present invention.
In FIG. 3, the IGBT 34 is screwed to a heat sink 33 connected to the ground potential for heat dissipation. For example, in a three-phase inverter, three IGBTs 34 for the upper arm and three IGBTs 34 for the lower arm can be screwed to the same heat sink 33 as a set.
A printed pattern 32 b is formed on the front surface of the printed circuit board 31, and a printed pattern 32 a is formed on the back surface of the printed circuit board 31. Here, the printed pattern 32b is arranged on the surface of the printed circuit board 31 so as to cover the area where the printed pattern 32a and the heat sink 33 overlap, and has a minimum area necessary for securing the current flowing through the printed pattern 32b. Can be set.

The IGBT 34 screwed to the heat sink 33 is mounted on the front surface side of the printed circuit board 31, and a terminal whose potential does not vary by the switching operation of the IGBT 34 is connected to the printed pattern 32 b, and the potential is switched by the switching operation of the IGBT 34. The terminal where is fluctuated is connected to the print pattern 32a.
For example, when a three-phase inverter is configured using the IGBT 34, the terminals connected to the upper and lower arm connection points are connected to the print pattern 32a, and the terminals connected to the positive and negative electrodes of the power converter are connected to the print pattern 32b. be able to. Here, even when a stray capacitance is formed between the print pattern 32 b and the heat sink 33, the common mode current does not flow because the potential does not fluctuate due to the switching operation of the IGBT 34. On the other hand, by forming the print pattern 32b so as to face the print pattern 32a, the electrostatic coupling between the print patterns 32a and 32b can be strengthened, and the electric lines of force reaching the heat sink 33 from the print pattern 32a are printed. It can be shielded by the pattern 22b.

  As a result, even when the print pattern 32a and the heat sink 33 are arranged in an overlapping manner, the stray capacitance C31 formed between the print pattern 32a and the heat sink 33 can be reduced, and an increase in mounting area is suppressed. However, it is possible to suppress an increase in common mode current due to the layout when the IGBT 34 is mounted.

FIG. 4 is a cross-sectional view illustrating an IGBT mounting method for a power conversion device according to a fourth embodiment of the present invention.
In FIG. 4, the IGBT 44 is screwed to a heat sink 43 connected to the ground potential for heat dissipation. For example, in a three-phase inverter, three IGBTs 44 for the upper arm and three IGBTs 44 for the lower arm can be screwed to the same heat sink 43 as a set.

  A printed pattern 42 b is formed on the front surface of the printed circuit board 41, and a printed pattern 42 a is formed on the back surface of the printed circuit board 41. Here, the printed pattern 42b is arranged on the surface of the printed circuit board 41 so as to cover the area where the printed pattern 42a and the heat sink 43 overlap, and the printed pattern 42b and the heat sink 43 overlap the printed pattern 42a and the heat sink 43. It is possible to set the area to be larger than the area where 43 overlaps. The IGBT 44 screwed to the heat sink 43 is mounted on the surface side of the printed circuit board 41, and a terminal whose potential does not vary by the switching operation of the IGBT 44 is connected to the printed pattern 42b, and the potential by the switching operation of the IGBT 44. The terminal where is fluctuated is connected to the print pattern 42a.

  For example, when a three-phase inverter is configured using the IGBT 44, the terminals connected to the upper and lower arm connection points are connected to the printed pattern 42a, and the terminals connected to the positive and negative electrodes of the power converter are connected to the printed pattern 42b. be able to. Here, even when stray capacitance is formed between the print pattern 42 b and the heat sink 43, the common mode current does not flow because the potential does not fluctuate due to the switching operation of the IGBT 44. On the other hand, by forming the print pattern 42b so as to face the print pattern 42a, the electrostatic coupling between the print patterns 42a and 42b can be strengthened, and the electric flux reaching the heat sink 43 from the print pattern 42a is changed to the print pattern. It can be shielded by 42b.

  As a result, even when the print pattern 42 a and the heat sink 43 are arranged so as to overlap each other, the electric lines of force reaching the heat sink 43 from the print pattern 42 a can be reduced and formed between the print pattern 42 a and the heat sink 43. Since the stray capacitance C41 can be reduced, it is possible to suppress an increase in common mode current due to a layout when the IGBT 44 is mounted while suppressing an increase in mounting area.

FIG. 5: is sectional drawing which shows the mounting method of IGBT of the power converter device which concerns on 5th Embodiment of this invention.
In FIG. 5, a 2-in-1 type IGBT 54 is screwed to a heat sink 53 connected to the ground potential for heat dissipation. A printed pattern 52 is formed on the surface of the printed circuit board 51, and the printed pattern 52 is drawn out to the back surface of the printed circuit board 51 through a through hole 57. The electrode 56 connected to the output terminal of the IGBT 54 is connected to the print pattern 52 via the bus bar 55.
Here, the print pattern 52 can be connected to a terminal whose potential fluctuates by the switching operation of the IGBT 54. For example, when a three-phase inverter is configured using the IGBT 54, it can be connected to the upper and lower arm connection points. .

  When the area of the print pattern 52 is large, the print pattern 52 can be arranged so as to face the heat sink 53. The reason for this configuration is as follows. A printed circuit board is at most about 1 to 2 mm thick, whereas FR4 generally used for a board has a relative dielectric constant of about 4 to 5. By drawing a pattern on the back surface of the substrate, the inter-electrode distance of the stray capacitance is increased by about 1 to 2 mm. However, since the substrate relative permittivity is larger than the atmosphere (relative permittivity 1), the capacitance increases. . Therefore, when it is difficult to shield with another print pattern, the problem of stray capacitance is smaller and the leakage current is less when the pattern whose potential fluctuates greatly due to switching is arranged at a position facing the heat sink.

Here, when the print pattern 52 is disposed so as to face the heat sink 53, it is set to a minimum necessary area for securing a current flowing through the print pattern 52.
Thus, even when the print pattern 52 and the heat sink 53 are arranged to face each other, the area of the print pattern 52 can be reduced as much as possible. Therefore, the print pattern 52 and the heat sink 53 are formed. The stray capacitance C51 can be reduced. For this reason, it becomes possible to suppress the increase in the common mode current resulting from the layout when the IGBT 54 is mounted, and it is possible to reduce conduction noise and radiation noise.

  In the above-described embodiment, the IGBT is described as an example of the switching element, but a power MOSFET or a bipolar transistor may be used. In the above-described embodiment, the method of configuring a three-phase inverter using discrete IGBTs has been described as an example. However, the present invention can be applied regardless of the number of arms of the inverter and the type of semiconductor.

Furthermore, in the above-described embodiment, the case where the heat sink is grounded has been described as an example. However, the present invention may be applied when the heat sink is not grounded.
In the above-described embodiment, the inverter configured by a series circuit of switching arms has been described as an example. However, the present invention may be applied to a power conversion apparatus including only one switching element.

FIG. 6 is a circuit diagram showing a schematic configuration of the power conversion device according to the sixth embodiment of the present invention.
In FIG. 6, in the flyback converter, the primary side of the transformer 62 is connected to the upper arm side instead of the switching element M11 and the feedback diode D11 of FIG. A parallel circuit of a capacitor C61 and a resistor R61 is connected to the secondary side of the transformer 62 via a diode D61.

  Here, if the connection point between the transformer 62 and the switching element M14 is connected to the print pattern 61, the heat sink used for heat dissipation of the switching element M14 can be arranged at a position not facing the print pattern 61. Alternatively, a printed pattern whose potential does not change by the switching operation of the switching element M14 is formed on the surface of the printed board, and a printed pattern whose potential changes by the switching operation of the switching element M14 is formed on the back surface of the printed board. A heat sink used for heat dissipation of the element M14 may be disposed on the surface of the printed board.

  This makes it possible to reduce the stray capacitance formed between the printed pattern 61 and the heat sink even when applied to a power conversion device having only one switching element, and at the time of mounting the switching element M14. It is possible to suppress an increase in common mode current due to the layout.

11, 21, 31, 41, 51 ... Printed circuit boards 12, 22a, 22b, 32a, 32b, 42a, 42b, 52 ... Print patterns 13, 23, 33, 43, 53 ... Heat sinks 14, 24, 34, 44, 54 ... IGBT
55 ... Bus bar 56 ... Electrode 57 ... Through hole C11, C21, C31, C41, C51 ... Floating capacitance

Claims (2)

A semiconductor switching element that performs a switching operation;
A printed circuit board on which the semiconductor switching element is mounted on the surface side;
A conductor disposed on the surface side of the printed circuit board and dissipating heat generated from the semiconductor switching element;
A first printed pattern formed on the surface side of the printed circuit board and connected to a terminal whose potential does not vary in the switching operation of the semiconductor switching element;
A second printed pattern formed on the back side of the printed circuit board and connected to a terminal whose potential varies in the switching operation of the semiconductor switching element ,
The power conversion device , wherein the first print pattern is arranged so as to cover a region where the second print pattern and the conductor overlap . 2. The power converter according to claim 1 , wherein a region where the first print pattern and the conductor overlap has a larger area than a region where the second print pattern and the conductor overlap .

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