Power conversion device

Abstract

Power conversion device (2) comprising: a power semiconductor module (3a, 3b) configured to convert power; a first capacitor (6) configured to smooth the power; a conductor section (10a, 10b) forming a first power path (11a, 11b) between a power terminal (4) and the first capacitor (6) and a second power path (12a, 12b) between the first capacitor (6) and the power semiconductor module (3a, 3b); a noise filter section (20) including a second capacitor (22) that smooths a power having a higher frequency than a frequency of the power smoothed by the first capacitor (6); and a cooling section (25) forming a cooling surface (24), wherein the interference filter section (20) is connected to the conductor section (10a, 10b) forming the first power path (11a, 11b), and the conductor section (10a, 10b) forming the first power path (11a, 11b) is arranged in a space between the cooling surface (24) and the noise filter section (20), wherein a line section connecting a substantially central section of the first capacitor (6) and a substantially central section of the noise filter section (20) is defined as a first line segment, a connecting section between the first power path (11a, 11b) and the noise filter section (20) is arranged on one side with respect to the first line segment as a boundary, and the second power path (12a, 12b) and the first capacitor (6) are arranged on the other side with respect to the first line segment as a boundary, characterized by the fact that the first power path (11a, 11b) is formed such that a surface of the first power path (11a, 11b) where the connecting portion between the first power path (11a, 11b) and the noise filter portion (20) is provided becomes substantially parallel to the first line segment, and the second power path (12a, 12b) is formed such that a surface of the second power path (12a, 12b), where a connecting portion between the second power path (12a, 12b) and the first capacitor (6) is provided, becomes substantially parallel to the first line segment. 2. The power conversion device according to claim 1, wherein

Description

Technical area

[0001] The present invention relates to a power conversion device, and more particularly to a power conversion device that drives an electric vehicle drive rotating machine. Background area

[0002] In a main circuit and capacitor module of a power conversion device mounted on hybrid vehicles and electric vehicles, a power terminal connected to a power supply for supplying DC power and a power semiconductor module for converting DC power into AC power are connected by a conductor portion. A capacitor cell for smoothing the DC power is connected to the conductor portion.

[0003] With the recent size reduction and higher current and voltage of power conversion, the capacitor cell receives heat inflow due to power loss at the time of power conversion due to a high temperature environment, and side effects such as destruction and deterioration become apparent, and a structure that effectively performs cooling is required.

[0004] The power conversion device mounted on hybrid vehicles and electric vehicles is required to take measures against electromagnetic interference (hereinafter electromagnetic compatibility interference (EMC interference)) that is generated and becomes large with the progress of higher voltage and larger current and higher radio frequency of the switching elements.

[0005] To suppress EMC interference, adding a noise filter circuit is effective. However, one issue is that the impedance of the power path needs to be increased. Therefore, the wiring becomes long, the cross-sectional area becomes small, and power loss (heat generation) increases. Side effects such as deterioration of the components forming a noise filter become apparent due to the influence of heat, and a structure that effectively performs cooling is required.

[0006] PTL 2 describes a power conversion device for vehicles. A suppression capacitor is electrically connected to an input-side power supply terminal of the capacitor module at a position where the distance between a junction of the suppression capacitor and the input-side power supply terminal is shorter than the distance between the junction of the suppression capacitor and an output-side power supply terminal of the capacitor module. Citation listPatent literature PTL 1: JP 2014 - 128084 A PTL 2: JP 2013 - 220 029 A Summary of the inventionTechnical problem

[0007] An object of the present invention is to improve the reliability of a power conversion device having an effective cooling structure. Solution to the problem

[0008] The object is achieved by a power conversion device according to the appended patent claims, wherein the dependent patent claims describe preferred technical developments. Advantageous effects of the invention

[0009] According to the present invention, the reliability of a power conversion device can be improved. Brief description of the drawings Fig. 1 is a circuit diagram relating to a switching circuit section and a noise filter section in a power conversion device. Fig. 2(a) is a partial perspective view of a power conversion device 2 for describing a cooling structure of a noise filter section 20. Fig. 2(b) is a cross section of an area S in Fig. 2(a) viewed in a direction of arrow A. Fig. 2(c) is a cross-sectional view for describing an arrangement of a first capacitor 6 and the noise filter section 20. Fig. 3(a) is a circuit diagram illustrated for detecting an impedance component present in the noise filter section 20 shown in Fig. 1 is illustrated. Fig. 3(b) is a layout diagram in which a second capacitor 25 is configured to be sandwiched between a first power path 11a of a conductor portion 10a and a first power path 11b of a conductor portion 10b and a cooling portion 25, as a comparative example. Fig. 3(c) illustrates the present embodiment and is a layout diagram in which a first power path 11a of a conductor portion 10a and a first power path 11b of a conductor portion 10b are configured to be sandwiched between a second capacitor 25 and a cooling portion 25. Description of the embodiments

[0010] The background art according to an embodiment of the present invention and problems according to the embodiment are described in detail below.

[0011] In recent years, attention has been paid to hybrid vehicles and electric vehicles for the purpose of reducing environmental pollution and resource consumption, in order to respond to improving fuel consumption and emission control, and hybrid vehicles and electric vehicles are becoming internationally popular.

[0012] In response to such trends, electromagnetic compatibility (EMC) problems such as electromagnetic interference to the environment of automotive electronic equipment and resistance to electromagnetic interference from the environment are increasing, and measures against the problems are an issue for automotive electronic equipment.

[0013] Particularly in Europe, compliance with European Directive 2004 / 104 / EC (EMC Directive for motor vehicles) for electronic equipment for motor vehicles is strictly required, and EMC certification is carried out for the electric vehicles themselves and for electrical and electronic components and assembled components mounted on the vehicles.

[0014] Furthermore, the United Nations Economic Commission for Europe (UNECE) promoted the harmonization of international standards, and ECE Reg. 10.03 (Radio Interference Suppression) was established as an international standard. Furthermore, the EMC requirements for electric vehicles and plug-in hybrid vehicles, supplementing ECE Reg. 10.04, were published in March 2011. The EMC law for domestic motor vehicles (ECE Reg. 10.05) was published in August 2011. Furthermore, it is necessary to master not only the laws and regulations of each country, but also the requirements of each manufacturer's own standard.

[0015] Meanwhile, a power conversion device, one of the electrical components mounted on a vehicle, is a device that handles high voltage and high current and performs power conversion through high-speed switching, thus becoming a source of EMC noise. Furthermore, the operating time and operating state (high output torque state) of a motor driven by the power conversion device are expected to increase in the future, and EMC noise will become greater with ever-higher power conversion voltage and current and the higher radio frequency of the switching element, and mitigating loss by reducing the loss is considered essential.

[0016] To suppress the EMC noise generated by the power conversion device, a measure to dispose a noise filter module on an output side of a power terminal from which noise caused by switching operation flows out is effective. However, as an issue, the wiring from the switching element to the input of the power terminal becomes long, the cross-sectional area becomes small, and power loss (heat generation) increases, from the viewpoint that a space is required for disposing components such as a capacitor and a core that constitute a noise filter circuit, and from the viewpoint that the impedance of a power path must be increased to suppress the noise from the switching element to the input of the power terminal.

[0017] Therefore, side effects such as destruction or deterioration of components constituting a noise filter become apparent due to the influence of the generated heat, and a structure that effectively cools the heat generation is required. To solve this problem, in the present embodiment, a power path that becomes a heat generation source is arranged close to a water channel surface of an inverter case, and a noise filter module is arranged in a space above the inverter case, thereby improving heat dissipation performance and enabling a high output of the inverter. In addition, since the amount of heat flowing from the power path into the noise filter module via a connection terminal is reduced, the effect of the thermal resistance / impedance of the connection terminal on the temperature inside the noise filter is reduced.This allows the degree of freedom in designing a wiring impedance to improve a noise filtering function such as forming the connection terminal with a low impedance and an equal PN length to be obtained.

[0018] Fig. 1 is a circuit diagram relating to a switching circuit section 3 and a noise filter section in a power conversion device 2.

[0019] The switching circuit section 3 converts a DC power of a high-voltage battery 1 into an AC power for driving a motor generator MG.

[0020] A power semiconductor module 3a forms a component of the switching circuit section 3 and is connected to a U-phase of the motor generator MG. A power semiconductor module 3b forms a component of the switching circuit section 3 and is connected to a V-phase of the motor generator MG. A power semiconductor module 3c forms a component of the switching circuit section 3 and is connected to a W-phase of the motor generator MG. The first capacitor 6 smoothes the DC power to be supplied to the switching circuit section 3.

[0021] A conductor portion 10a and a conductor portion 10b are connected to the high-voltage battery 1 and the power semiconductor modules 3a to 3c. Note that the conductor portion 10a constitutes a positive-electrode-side conductor portion, and the conductor portion 10b constitutes a negative-electrode-side conductor portion.

[0022] A power terminal 4 connects the conductor section 10a and the conductor section 10b to the high-voltage battery 1. A power-side terminal 5 connects the conductor section 10a and the conductor section 10b to the switching circuit section 3.

[0023] A first power path 11a is a positive electrode side power path between the power terminal 4 and the first capacitor 6 in the conductor section 10a. A first power path 11b is a negative electrode side power path between the power terminal 4 and the first capacitor 6 in the conductor section 10b.

[0024] A second power path 12a is a positive electrode side power path between the first capacitor 6 and the power semiconductor modules 3a to 3c in the conductor section 10a. A second power path 12b is a negative electrode side power path between the first capacitor 6 and the power semiconductor modules 3a to 3c in the conductor section 10b.

[0025] A noise filter section 20 is formed by a ground 21 in the circuit of the power conversion device 2 and a second capacitor 22 that smoothes a power having a frequency higher than a frequency of the power smoothed by the first capacitor 6.

[0026] An X capacitor 22x is a capacitor connected between a positive electrode and a negative electrode of conductor section 10, which smooths power. A Y capacitor 22y is a capacitor connected between conductor section 10a and ground 21, and between conductor section 10b and ground 21, which smooths power.

[0027] Fig. 2(a) is a partial perspective view of the power conversion device 2 for describing a cooling structure of the noise filter section 20. Fig. 2(b) is a cross section of an area S in Fig. 2(a) viewed in a direction of arrow A.

[0028] A housing 7 forms a space in which the first capacitor 6 is housed and forms a space in which the noise filter section 20 is arranged. The housing 7 is mainly made of metal, in particular aluminum.

[0029] A flow path 8 is formed at a position facing a bottom portion of the first condenser 6. The flow path 8 may be provided so as to be formed inside the casing 7, or may be configured by a member different from the casing 7 and provided so as to be connected to the casing 7.

[0030] A cooling surface 24 is connected to the first power path 11a of the conductor section 10a and the first power path 11b of the conductor section 10b in the housing 7. A cooling section 25 is formed at a position facing the cooling surface 24. It should be noted that the cooling section 25 may be a flow path connected to the flow path 8.

[0031] Fig. 3(a) is a circuit diagram illustrated for detecting an impedance component present in the noise filter section 20 shown in Fig. 1 is illustrated. Fig. 3(b) is a layout diagram in which a second capacitor 25 is configured to be sandwiched between a first power path 11a of a conductor portion 10a and a first power path 11b of a conductor portion 10b and a cooling portion 25, as a comparative example. Fig. 3(c) illustrates the present embodiment and is a layout diagram in which the first power path 11a of the conductor portion 10a and the first power path 11b of the conductor portion 10b are configured to be sandwiched between the second capacitor 25 and the cooling portion 25.

[0032] In the comparative example, the heat generation of the first power path 11a and the first power path 11b is dissipated to the cooling section 25 via the second capacitor 22, which is a constituent component of the noise filter section 20. That is, the heat generation of the first power path 11a and the first power path 11b passes through a thermal resistance Rth1 of the second capacitor 22 and a thermal resistance Rth2 from the second capacitor 22 to the cooling section 25.

[0033] It should be noted that a capacitor terminal 22a connects the conductor portion 10a provided with the first power path 11a and the second capacitor 22, and a capacitor terminal 22b connects the conductor portion 10b provided with the first power path 11b and the second capacitor 22.

[0034] In contrast, in the present embodiment shown in Fig. 3(c), the heat generation Qbus of the first power path 11a and the first power path 11b via the second capacitor 22, which is similar to that in Fig. 3(b), and a heat dissipation path (thermal resistance Rth3) connected from the first power path 11a and the first power path 11b in parallel directly to the cooling section 25 to a heat dissipation path (thermal resistance Rth1 + Rth2).

[0035] Here, the thermal resistance Rth1 + Rth2 is compared with the thermal resistance Rth3, and Rth3 << Rth1 + Rth2 is consistent with the structure in Fig. 3(c), in which the heat dissipation path has a wider area and is connected at a short distance. For example, if Rth3 = (Rth1 + Rth2) / 10, the following simultaneous equations 1 to 4 are solved, wherein a temperature rise of the first power path 11a and the first power path 11b to the cooling section 25 in Fig. 3(b) ΔTth12 is a temperature increase of the thermal resistance Rth1 + Rth2 in Fig. 3(c) is ΔTth12' and a temperature rise of the thermal resistance Rth3 is ΔTth3. Qbus=ΔTth12 / (Rth1+Rth2) Qbus=(ΔTth12' / (Rth1+Rth2))+(ΔTth3 / Rth3) ΔTth12'=ΔTth3 Rth3=(Rth1+Rth2) / 10

[0036] As a result, ΔTth12' = ΔTth12 / 11 is obtained, and thus it is determined that the temperature rise from the first power path 11a and from the first power path 11b to the cooling section 25 in Fig. 3(c) e.g. to 1 / 11 compared to Fig. 3(b) and the heat dissipation performance is improved.

[0037] Furthermore, since the temperature rise ΔTth2 of the second capacitor 22 utilizes ΔTth12 in the ratio of the thermal resistance Rth1 and the thermal resistance Rth2, ΔTth2 has been conventionally designed to be less than or equal to the heat-resistant temperature 105 °C of a capacitor element of the second capacitor 22 by setting Rth1 >> Rth2.

[0038] Here, as a technique for making the thermal resistance Rth1 large, an electrical connection structure between the first power paths 11a and 11b to the second capacitor, for example, the cross-sectional areas of the capacitor terminal 22a and the capacitor terminal 22b, was made small, and a wiring length was made long. However, with an increase in the thermal resistance, the impedance Ztm also increases simultaneously, which hinders the flow of noise current into the second capacitor 22 and may deteriorate the noise filtering function.

[0039] In contrast, in the present embodiment, the temperature rise ΔTth12' itself from the first power path 11a and from the first power path 11b to the cooling section 25 is reduced by adding the thermal resistance Rth3. Therefore, the effect on ΔTth2 due to making the thermal resistance Rth1 large is reduced accordingly.

[0040] Therefore, the thermal resistance and impedance of the capacitor terminal 22a and the capacitor terminal 22b can be made smaller than in the conventional case, and ΔTth2 can be made less than or equal to the heat resistance temperature 105 °C of the capacitor without deteriorating the noise filtering function.

[0041] In other words, the effect on the impedance Ztm of the capacitor terminal 22a and the capacitor terminal 22b with respect to the temperature rise in the noise filter section 20 is further reduced. The degree of freedom in designing a wiring structure for improving the noise filtering function, such as forming an electrical connection from the first power path 11a and the second power path 11b to the second capacitor 22 with a low impedance and an equal PN length, is obtained.

[0042] In addition, the conductor section 10a, which is Fig. 2(a), the first power path 11a is formed such that the cross-sectional area of ​​the first power path 11b becomes smaller than the cross-sectional area of ​​the second power path 12a. Likewise, the conductor portion 10b is formed such that the cross-sectional area of ​​the first power path 11b becomes smaller than the cross-sectional area of ​​the second power path 12b. As a result, the first power path 11a and the first power path 11b are formed to have high impedance, and transmission of a radio frequency voltage fluctuation at the time of the DC / AC conversion operation of the switching circuit portion 3 to the power terminal 4 can be suppressed. Therefore, the noise filtering function of the noise filtering portion 20 can be improved.

[0043] Fig. 2(c) is a cross-sectional view for describing an arrangement of the first capacitor 6 and the noise filter section 20.

[0044] A line segment 30 is a line segment connecting a substantially central portion of the first capacitor 6 and a substantially central portion of the noise filter portion 20. Note that the substantially central portion of the first capacitor 6 and the substantially central portion of the noise filter portion 20 are the respective center of gravity positions.

[0045] A space 31 is a space on one side with respect to the first line segment 30 as a boundary, and a space 32 is a space on the other side opposite to the first space 31 with respect to the first line segment 30 as a boundary.

[0046] In the present embodiment, a first connection portion between the first capacitor 6 and the conductor portion 10a is provided on the space 31 side, and a second connection portion between the noise filter portion 20 and the conductor portion 10a is provided on the space 31 side. As a result, the distance between the first connection portion and the second connection portion is larger than in a case where the first connection portion and the second connection portion are provided in the space 31.

[0047] Here, a capacitive coupling C and a magnetic coupling M formed between the first power paths 11a and 11b and the second power paths 12a and 12b are expressed by the following equations 5 and 6. Here, ε0: vacuum permittivity, µ0: vacuum permeability, S: a contact area between the first and second power paths, and d: a distance between the first and second power paths. The capacitive coupling C=ε0*(S / d) The magnetic coupling M=μ0*(S / d)

[0048] Both the capacitive coupling C and the magnetic coupling M are inversely proportional to the distance d between the first power paths 11a and 11b and the second power paths 12a and 12b. Furthermore, a noise component caused by a radio frequency voltage fluctuation at the time of the DC / AC conversion operation of the switching circuit section 3 propagates through space due to the capacitive coupling C and the magnetic coupling M. Therefore, according to the present embodiment, when the distance between the first connection section and the second connection section is caused to be large, the noise propagating through space from the second power paths 12a and 12b to the first power paths 11a and 11b can be suppressed, and the noise filtering function can be improved.

[0049] As in Fig. As illustrated in Fig. 2(c), the first power paths 11a and 11b are formed such that the surfaces 11d and 11d of the first power paths 11a and 11b, where the connecting portion with the noise filter portion 20 is provided, become substantially parallel to the line segment 30, and the second power paths 12a and 12b are formed such that the surfaces 12c and 12d of the second power paths 12a and 12b, where the connecting portion with the first capacitor 6 is provided, become substantially parallel to the line segment 30. With this structure, the first power paths 11a and 11b, where the connecting portion with the noise filter portion 20 is provided, can have a small influence on the noise radiated from the switching circuit portion 3.

[0050] As further stated in Fig. As illustrated in Figure 2(c), an end portion of the first power paths 11a and 11b, the end portion closest to the second power paths 12a and 12b, is defined as a first end portion 40. The noise filter portion 20 is disposed at a position in a direction 41 away from the second power paths 12a and 12b and separated from the first end portion 40.

[0051] When the second capacitor 22 constituting the noise filter section 20 is arranged in a direction approaching the second power paths 12a and 12b (a position 22c of the comparative example in Fig. 2(c)), the distance between the second capacitor 22 and the second power paths 12a and 12b is defined as d1.

[0052] The capacitive coupling is defined as C1, and the magnetic coupling is defined as M1 when the second capacitor 22 is located at the position 22c of the comparative example.

[0053] d2 > d1, C2 < C1 and M2 < M1 are arranged, wherein the distance between the second capacitor 22 and the second power paths 12a and 12b is d2, the capacitive coupling is C2 and the magnetic coupling is M2 when the second capacitor 22 is located at the position shown in Fig. 2(c). Therefore, the noise propagating from the second power paths 12a and 12b to the second capacitor 22 through space can be suppressed, and the noise filtering function can be improved.

[0054] In addition, the first power paths 11a and 11b of the conductor sections 10a and 10b are in contact with a heat dissipation member 13 in contact with the cooling section 25. As a result, the cooling performance of the first power paths 11a and 11b can be improved. List of reference symbols 1 high-voltage battery 2 Power conversion device 3 Switching circuit section 3a Power semiconductor module 3b Power semiconductor module 4 Power connection 6 first capacitor 7 housings 8 Flow path 10a Ladder section 10b Ladder section 11a first performance path 11b first performance path 11d area 11d area 12a second performance path 12b second performance path 20 Noise filter section 21 Mass 22 second capacitor 22a capacitor connection 22b Capacitor connection 22c Position of the comparative example 24 cooling surface 25 Cooling section 30 line segments 31 Room 32 rooms 40 first final section 41 Direction away from the second power paths 12a and 12b

Claims

[1] Power conversion device (2) comprising: a power semiconductor module (3a, 3b) configured to convert power; a first capacitor (6) configured to smooth the power; a conductor section (10a, 10b) forming a first power path (11a, 11b) between a power terminal (4) and the first capacitor (6) and a second power path (12a, 12b) between the first capacitor (6) and the power semiconductor module (3a, 3b); a noise filter section (20) including a second capacitor (22) that smooths a power having a higher frequency than a frequency of the power smoothed by the first capacitor (6); and a cooling section (25) forming a cooling surface (24), wherein the interference filter section (20) is connected to the conductor section (10a, 10b) forming the first power path (11a, 11b), and the conductor section (10a, 10b) forming the first power path (11a, 11b) is arranged in a space between the cooling surface (24) and the noise filter section (20), wherein a line section connecting a substantially central section of the first capacitor (6) and a substantially central section of the noise filter section (20) is defined as a first line segment, a connecting section between the first power path (11a, 11b) and the noise filter section (20) is arranged on one side with respect to the first line segment as a boundary, and the second power path (12a, 12b) and the first capacitor (6) are arranged on the other side with respect to the first line segment as a boundary, characterized by the fact that the first power path (11a, 11b) is formed such that a surface of the first power path (11a, 11b) where the connecting portion between the first power path (11a, 11b) and the noise filter portion (20) is provided becomes substantially parallel to the first line segment, and the second power path (12a, 12b) is formed such that a surface of the second power path (12a, 12b), where a connecting portion between the second power path (12a, 12b) and the first capacitor (6) is provided, becomes substantially parallel to the first line segment.

2. The power conversion device according to claim 1, wherein [2] The power conversion device according to claim 1, wherein a cross-sectional area of ​​the first power path (11a, 11b) of the conductor portion is smaller than a cross-sectional area of ​​the second power path (12, 12b). [3] Power conversion device according to claim 1 or 2, wherein an end section of the first power path (11a, 11b), the end section being closest to the second power path (12a, 12b), is defined as a first end section (40), and the noise filter section (20) is arranged at a position in a direction (41) away from the second power path (12a, 12b) and separated from the first end section (40). [4] A power conversion device according to any one of claims 1 to 3, further comprising: a heat dissipation element (13) arranged between the conductor portion forming the first power path (11a, 11b) and the cooling surface (24) and in contact with the conductor portion and the cooling surface (24).

Images