JP2016005302A - Power conversion apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress noise of a power conversion apparatus.SOLUTION: The power conversion apparatus includes: a ground capacitor having one end connected with an input section of the power conversion apparatus and the other end connected with a ground line; a common mode core provided for a power line connecting an output section of the power conversion apparatus with a load; and an inductance element connected between the ground line and a ground on the power supply side.

Description

  The present invention relates to a power conversion device, and more particularly to a power conversion device that involves a switching operation of a semiconductor element.

  The power conversion device converts, for example, power from a power source and supplies it to a load. Usually, a power source, a power converter, and a load are arranged in a closed circuit by a power line. Therefore, a current having a phase opposite to that of the current supplied from the power converter to the load is fed back from the load to the power converter.

  Power converters often involve switching operations of power semiconductor elements. High frequency components can be generated as conductive noise by the switching operation. Since noise current flows when noise is generated, measures for reducing the noise current are required.

  Since the noise current includes a high-frequency component, it can be coupled from the power line to another electric circuit. Due to the coupling, for example, a part of the noise current flows through the ground wire or the ground. The noise current that returns to the power conversion device via the ground line or the ground is a common mode current having the same phase and the same amplitude as the current supplied from the power device to the load. In order to reduce the noise current, it is important to reduce the common mode current.

  In the power converter system proposed by Japanese Patent Laying-Open No. 2008-295126 (Patent Document 1), each phase of the input unit of the inverter device is connected to a radiator via a ground capacitor (ground capacitor). A motor (load) is connected to the output unit of the inverter device, and the motor is housed in a frame (housing). The frame is electrically connected to the radiator. Here, the frame is connected to a ground (ground) earth using an impedance element. According to this configuration, the frame and the heat radiator are connected to the ground via the impedance element instead of directly. Therefore, the common mode current flowing through the ground can be reduced.

  In the semiconductor power module proposed by Japanese Patent Laying-Open No. 2008-42124 (Patent Document 2), the rectifier circuit and the inverter circuit are respectively disposed on the metal base plate on the cooling body (heat radiator). Here, the cooling body (and the metal base plate) is divided into a rectifier circuit side and an inverter circuit side, and is connected via an impedance element. According to this configuration, it is possible to suppress the noise current generated by the switching operation of the semiconductor chip included in the inverter circuit from flowing through the ground wire on the input side (rectifier circuit side).

JP 2008-295126 A JP 2008-42124 A

  The technique proposed in Patent Document 1 can reduce the common mode current flowing through the ground, but cannot reduce the common mode current flowing through the ground wire. Therefore, it is not sufficient to suppress noise of the power conversion device.

  The technique proposed in Patent Document 2 can reduce the common mode current flowing through the ground wire (heat radiator), but cannot reduce the common mode current flowing through the ground. Therefore, it is not sufficient to suppress noise of the power conversion device.

  The objective of this invention is suppressing the noise of a power converter device.

  A power converter according to the present invention is a power converter that converts power from a power source and supplies the power to a load. The power source is connected to the ground on the power source side. The load is housed in a housing to which a ground wire is connected. The power conversion device includes a ground capacitor, a common mode core, and an inductance element. The ground capacitor has one end connected to the input portion of the power converter and the other end connected to the ground wire. A common mode core is provided with respect to the power line which connects the output part of a power converter device, and load. The inductance element is connected between the ground wire and the ground on the power supply side.

  In the power converter configured as described above, the common mode current flowing through the power line is reduced by the common mode core. Further, the inductance element 260 also reduces the common mode current flowing from the ground wire to the ground on the power source side. The combination of the common mode core and the inductance element 260 can reduce both the common mode current flowing through the ground wire and the common mode current flowing through the ground.

  According to the present invention, it is possible to suppress noise in the power conversion device.

It is a figure for demonstrating the power converter device 200 which concerns on Embodiment 1. FIG. 4 is a perspective view for explaining an example of a structure of a power conversion device 200. FIG. FIG. 5 is a diagram for explaining an arrangement relationship between a substrate 210 and an inductance element 260. It is a figure for demonstrating 200 A of power converter devices which concern on Embodiment 2. FIG. It is a figure for demonstrating the power converter device 200B which concerns on Embodiment 3. FIG. It is a figure for demonstrating the power converter device 200E as a comparative example.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Unless otherwise specified, the same or corresponding parts in the drawings are denoted by the same reference numerals and description thereof will not be repeated.

[Embodiment 1]
FIG. 1 is a diagram for explaining a power conversion device 200 according to the first embodiment. Referring to FIG. 1, power conversion device 200 converts the power from power supply 100 and supplies it to load 400. The load 400 is typically a motor. However, the type of the load 400 is not particularly limited. For convenience of explanation, the ground wire EL is separately illustrated as ground wires EL1, EL2, and EL3.

  The power supply 100 generates three-wire AC power. The power source 100 is, for example, a system power source. The electric power from the power supply 100 is transmitted to the power conversion device 200 through three power lines PIL1, PIL2, and PIL3. The power supply 100 is connected to the ground (GND).

  Power conversion device 200 includes a rectifier circuit 220, an inverter circuit 230, a common mode core 240, cooling fins 250, capacitors C1 to C3, and an inductance element 260.

  Some components included in the power conversion device 200 are mounted on a substrate (not shown in FIG. 1). The type of component to be mounted is not particularly limited.

  In FIG. 1, terminals T <b> 1 to T <b> 3 are conceptually illustrated as input terminals of the power conversion device 200. The terminal TE is conceptually illustrated as a ground terminal. The terminal TE is a point located on the input side with respect to the inductor 260.

  Rectifier circuit 220 includes diodes D1 to D6, a capacitor C4, and input nodes N1 to N3.

  Input node N1 is a connection point of diodes D1 and D2. Input node N2 is a connection point of diodes D3 and D4. Input node N3 is a connection point of diodes D5 and D6. Power lines PIL1 to PIL3 are connected to input nodes N1 to N3, respectively. Therefore, power from the power supply 100 is input to the input nodes N1 to N3.

  The diodes D1 to D6 constitute a bridge circuit. The power input to the input nodes N1 to N3 is rectified by the bridge circuit.

  The capacitor C4 smoothes the power rectified by the bridge circuit. The smoothed power is supplied to the inverter circuit 230.

  Inverter circuit 230 includes switching elements SW1 to SW6 and output nodes Na to Nc.

  The switching elements SW1 to SW6 are power semiconductor elements. In the example shown in FIG. 1, IGBTs (Insulated Gate Bipolar Transistors) are shown as the switching elements SW1 to SW6, but the types of the switching elements SW1 to SW6 are not particularly limited. As the switching elements SW1 to SW6, for example, a power MOSFET (Metal Oxide Semiconductor Field Effect Transistor) may be used. A feedback diode is connected to each switching element SW1 to SW6.

  A control signal (not shown) is input to the control terminals (gates) of the switching elements SW1 to SW6. On / off (conduction / non-conduction) of the switching elements SW1 to SW6 is controlled by the control signal.

  The output node Na is a connection point between the switching elements SW1 and SW2. The output node Nb is a connection point between the switching elements SW3 and SW4. The output node Nc is a connection point between the switching elements SW5 and SW6. By controlling on / off of the switching elements SW1 to SW6, power for operating the load 400 can be generated in the output nodes Na to Nc. For example, when the load 400 is a three-phase motor, the power for operating the load 400 is three-phase AC power.

  The three-phase AC power generated at the output nodes Na to Nc is transmitted to the load 400 through the three power lines POL1 to POL3. Power lines POL <b> 1 to POL <b> 3 connect output portions (for example, output nodes Na to Nc) of power conversion device 200 and load 400.

  The common mode core 240 is a three-wire common mode core provided for the power lines POL1 to POL3. The common mode core 240 is formed of, for example, a ring-shaped core, and power lines POL1 to POL3 are wound around the ring. As the core, ferrite, amorphous, crystalline metal magnetic material or the like can be used.

  The common mode core 240 balances the current flowing through the power lines POL1 to POL3, that is, the current supplied from the power converter 200 to the load and the current returning from the load to the power converter (the sum is zero). Works. Therefore, the common mode current that can be generated by the switching operation of switching elements SW1 to SW6 of inverter circuit 230 can be suppressed from flowing through power lines POL1 to POL3.

  The cooling fin 250 is a radiator. The cooling fins 250 release the heat generated in the power conversion device 200 to the outside of the power conversion device 200. In the example shown in FIG. 1, the cooling fin 250 is connected between the ground wire EL2 and the ground wire EL3. Since the cooling fin 250 is made of a conductive member, the ground wire EL2 and the ground wire EL3 are electrically connected well. Therefore, the conductivity of the ground wire EL is not impaired.

  One end of capacitor C1 is connected to power line PIL1, and the other end is connected to ground line EL3. One end of capacitor C2 is connected to power line PIL2, and the other end is connected to ground line EL3. Capacitor C3 has one end connected to power line PIL3 and the other end connected to ground line EL3. That is, capacitors C1 to C3 are ground capacitors having one end connected to the input portion (for example, input nodes N1 to N3) of power conversion device 200 and the other end connected to ground line EL3. The common mode current can be fed back to the input portion of the power converter 200 via the capacitors C1 to C3.

  The inductance element 260 is connected between the ground line EL3 and the GND on the power supply 100 side. That is, one end of the inductance element 260 is connected to the ground wire EL3, and the other end of the inductance is connected to the GND on the power supply 100 side (via the terminal TE).

  Power line cable 300 bundles power lines POL1 to POL3 and ground line EL2. For example, when the distance between the power conversion device 200 and the load 400 is long, the power lines POL1 to POL3 and the ground line EL2 can be bundled by the power line cable 300 so that their wiring can be arranged.

  The load 400 is accommodated in the housing 410. A ground wire EL1 is connected to the housing 410. The ground wire EL1 is connected to the load-side GND.

  Since the load 400 is accommodated in the housing 410, there may be a parasitic capacitance between the load 400 and the housing 410. The parasitic capacitance is illustrated as “Cp1”.

  With the above configuration, a closed circuit including the power lines PIL1 to PIL3, the rectifier circuit 220, the inverter circuit 230, the common mode core 240, and the power lines POL1 to POL3 is formed between the power supply 100 and the load 400. Therefore, for example, the total sum of currents flowing through power lines POL1 to POL3 (the same applies to power lines PIL1 to PIL3) is basically zero.

  However, a harmonic component is generated as conductive noise by the switching operation of the inverter circuit 230. When noise is generated, a common mode current flows through the ground line EL and GND, and the sum of currents flowing through the power lines POL1 to POL3 deviates from zero.

Here, a path through which the common mode current can flow will be described with reference to a comparative example.
[Comparative example]
FIG. 6 is a diagram for explaining a power conversion device 200E as a comparative example. Referring to FIG. 6, power conversion device 200 </ b> E is different from power conversion device 200 in that it does not have capacitors C <b> 1 to C <b> 3 of FIG. 1, common mode core 240, and inductance element 260.

  FIG. 6 conceptually illustrates parasitic capacitances Cp1 to Cp3. The parasitic capacitance Cp1 exists between the load 400 and the housing 410. The parasitic capacitance Cp2 exists between the power lines POL1 to POL3 and the ground line EL2. The parasitic capacitance Cp3 exists between the inverter circuit 230 and the cooling fin 250.

  Due to the parasitic capacitances Cp1 to Cp3, there is a possibility that the common mode current generated in the inverter circuit 230 flows through the paths conceptually shown as the paths P1 to P4 in FIG.

  The path P1 includes the power line cable 300, the load 400, the parasitic capacitance Cp1, the ground line EL1, the load side GND, and the power source side GND in this order. Furthermore, the common mode current that has reached the power supply side GND returns to the input portion of the power conversion device 200 via the power supply 100 or the like, and this is the same for the paths P2 to P4.

  The path P2 includes the power line cable 300, the load 400, the parasitic capacitance Cp1, the ground line EL2, the cooling fin 250, and the ground line EL3 in this order.

  The path P3 includes the power line cable 300, the parasitic capacitance Cp2, the ground line EL2, the cooling fin 250, and the ground line EL3 in this order.

  The path P4 includes a parasitic capacitance Cp3, a cooling fin 250, and a ground line EL3 in this order.

  As described above, in the power conversion device 200E as the comparative example illustrated in FIG. 6, the common mode current can flow through the four paths P1 to P4. Therefore, in power converter 200E, possibility that a big noise will generate | occur | produce becomes high.

  On the other hand, referring to FIG. 1 again, power converter 200 according to the embodiment can reduce the common mode current by having capacitors C1 to C3, common mode core 240, and inductance element 260. . The reason for this is explained as follows.

  Since the inductance element 260 has a high impedance with respect to a high frequency, most of the common mode current flowing through the ground wire EL3 does not flow through the inductance element 260 but flows through the capacitors C1 to C3. For this reason, the common mode current flowing from the ground line EL3 to the GND on the power supply 100 side is reduced. That is, the inductance element 260 can reduce the common mode current flowing through the paths P2 to P4 shown in FIG.

  Here, instead of the inductance element 260, a common mode core (for example, the same as the common mode core 240) may be attached to the power lines PIL1 to PIL3. However, in this case, since all the three power lines of the power lines PIL1 to PIL3 must be wound around the common mode core, the winding portion becomes large and the apparatus may be increased in size. In particular, when the power consumption of the load 400 is large and a large current flows through the power lines PIL1 to PIL3, a large (thick) power line must be prepared as the power lines PIL1 to PIL3, and this problem becomes apparent. On the other hand, the inductance element 260 can be formed by winding a single wire around, for example, the core, and only a current smaller than the current flowing through the power lines PIL1 to PIL3 flows, thereby preventing an increase in the size of the device. Can do.

  Therefore, if an increase in the size of the device is allowed, an inductance element 260 may be provided, and a common mode core may be provided for power lines PIL1 to PIL3. As a result, it is possible to further suppress noise than when only the inductance element 260 is provided.

  On the other hand, the common mode core 240 can reduce the common mode current flowing through the power lines POL1 to POL3. That is, the common mode core 240 can reduce the common mode current flowing through the path P1 shown in FIG. Furthermore, as shown in FIG. 1, the common mode core 240 is disposed not on the load 400 side but on the power conversion device 200 side rather than the power line cable 300, thereby reducing the common mode current flowing through the power line cable 300. it can. That is, the common mode core 240 can reduce the common mode current flowing through the path P3 shown in FIG.

  As described above, according to the configuration shown in FIG. 1, the path caused by the parasitic capacitances Cp1 to Cp3, specifically, the ground line path such as the path P2 to P4 in FIG. The common mode current flowing through the path can be reduced. Therefore, it is possible to suppress noise generated in the power conversion device 200 rather than the power conversion device 200E as the comparative example of FIG.

  Note that the rectifier circuit 220 (the diodes D1 to D6 and the capacitor C4) and the cooling fin 250 illustrated in FIG. 1 are not essential elements for exhibiting a noise suppressing effect.

  Here, the noise suppression effect can be further enhanced by devising the arrangement of the inductance elements 260 in the power conversion device 200. This will now be described with reference to FIGS.

  FIG. 2 is a perspective view for explaining an example of the structure of the power converter 200. In FIG. 2, “U” indicates the upward direction of the power conversion apparatus 200, and “D” indicates the downward direction. “F” indicates an input side (corresponding to the power supply 100 side in FIG. 1) direction of the power conversion apparatus 200, and “R” indicates an output side (corresponding to the load 400 side in FIG. 1).

  Referring to FIG. 2, among the parts included in power conversion device 200 described above with reference to FIG. 1, for example, rectifier circuit 220, inverter circuit 230, common mode core 240, and cooling fin 250 An inductance element 260, capacitors C1 to C4, terminals T1 to T3, and a terminal TE are illustrated.

  Further, as shown in FIG. 2, the cooling fin 250 includes a notch 251 as a configuration not shown in FIG. 1. In addition, power conversion device 200 further includes a substrate 210 and an insulating member 270. The substrate 210 includes a substrate surface S.

  The substrate surface S is one mounting surface of the substrate 210. Capacitors C1 to C4 are mounted on the substrate surface S. In the example illustrated in FIG. 2, the substrate 210 is disposed so that the substrate surface S is directed upward (U direction). A rectifier circuit 220 and an inverter circuit 230 mounted in the module are disposed below the substrate 210 (D direction side).

  Terminals T1 to T3 and terminal TE are located on the input side (F direction side) of power conversion device 200.

The common mode core 240 is provided on the output side (R direction side) of the power conversion device 200.
The insulating member 270 is provided below the cooling fin 250 (D direction). The type of the insulating member 270 is not particularly limited. The merit of having the insulating member 270 is described as follows. That is, with reference to FIG. 1 and FIG. 2, the power converter device 200 is arrange | positioned, for example on the metal board which is not shown in the downward direction (D direction). In many cases, a metal board is set to the GND potential on the power supply side. If the power converter 200 does not have the insulating member 270, the cooling fin 250 and the metal board are in contact with each other, and both are electrically connected. As a result, the potential of the cooling fin 250 becomes the GND potential on the power supply side. When the potential of the cooling fin 250 becomes the GND potential on the power supply side, the inductance element 260 connected between the cooling fin 250 (and the ground wire EL3) and the GND on the power supply side is bypassed, so the inductance described above The effect by the element 260 cannot be obtained. On the other hand, the power converter 200 having the insulating member 270 can prevent the cooling fin 250 and the metal board from coming into contact with each other. Therefore, the effect by the inductance element 260 is reliably exhibited.

  The notch 251 is formed by cutting a part of the cooling fin 250. The notch 251 can have a shape and size suitable for the arrangement of the inductance element 260. In the example illustrated in FIG. 2, the notch 251 is formed by cutting one corner of the cooling fin 250, but the position of the notch 251 is not limited to this. That is, the cutout portion 251 may be provided at any location on the cooling fin 250 as long as a shield function described later is exhibited.

  Inductance element 260 is formed, for example, by winding a conducting wire around a cylindrical (or ring-shaped) core. The inductance element 260 may be formed by winding the ground wire EL3 around the core. The inductance element 260 is disposed in the notch 251.

  Here, when the inductance element 260 is mounted on the substrate 210, for example, a corresponding mounting space is required, and the power conversion device 200 is increased in size.

  On the other hand, by arranging the inductance element 260 in the notch 251, the power conversion device 200 can be made compact as a whole.

  In addition, when the inductance element 260 is mounted on the substrate 210, a circuit in the substrate 210 and a ground capacitor such as the capacitors C1 to C3 may be affected by leakage magnetic flux from the inductance element 260. Specifically, for example, when leakage magnetic flux passes through a circuit in the substrate 210, a new noise current (common mode current) may flow through the circuit due to interlinkage magnetic flux. Moreover, the parasitic inductance of the wiring of the capacitors C1 to C3 increases due to the leakage magnetic flux, and the capacitors C1 to C3 are likely to show inductivity with respect to the increase in frequency. As a result, the function as a ground capacitor is reduced, and most of the common mode current flowing through the ground wire EL3 flows through the inductance element 260 instead of the capacitors C1 to C3. Therefore, it becomes difficult to reduce the common mode current flowing through the paths P2 to P4 (more specifically, the portion passing through the ground line EL3 and the power supply side GND) shown in FIG.

  On the other hand, as shown in FIG. 2, when the inductance element 260 is arranged in the notch 251, the inductance element 260 is arranged at a position away from the substrate 210. Thereby, the influence which the board | substrate 210 receives from the leakage magnetic flux of the inductance element 260 can be reduced. In addition, since the cooling fin 250 plays a role of shielding the electromagnetic field (functions as a shield), the influence of the leakage magnetic flux can be further reduced.

  Here, the substrate 210 is disposed so that the substrate surface S is perpendicular to the vertical direction (UD direction), and the inductance element 260 is disposed so that the cylindrical core extends along the vertical direction (UD direction). Is preferred. By doing so, the influence of the leakage magnetic flux from the inductance element 260 can be minimized as will be described next with reference to FIG.

  FIG. 3 is a diagram for explaining the positional relationship between the substrate 210 and the inductance element 260. Referring to FIG. 3, the magnetic flux BL is conceptually illustrated as the leakage magnetic flux of the inductance element 260. From the winding direction of the inductance element 260, in the inductance element 260, the magnetic flux BL is generated in a direction perpendicular to the vertical direction (UD direction). The direction of the magnetic flux BL is parallel to the substrate 210. Therefore, the magnetic flux BL and the substrate 210 do not intersect. Therefore, the substrate 210 is hardly affected by the magnetic flux BL.

  Thus, by arranging the inductance element 260 so that the magnetic flux direction of the inductance element 260 and the surface direction of the substrate 210 are parallel, the influence of the magnetic flux BL on the substrate 210 can be reduced.

[Embodiment 2]
In the first embodiment, the common mode core 240 is provided for the power lines POL1 to POL3 (FIG. 1), and the method for reducing the common mode current has been described. In the second embodiment, a method for further reducing the common mode current by applying a modification of the common mode core will be described.

  FIG. 4 is a diagram for explaining a power conversion device 200A according to the second embodiment. Referring to FIG. 4, power conversion device 200 </ b> A is different from power conversion device 200 (FIG. 1) in that it includes a common mode core 240 </ b> A instead of common mode core 240 (FIG. 1). Since the structure of the other part of power converter 200A is the same as that of the corresponding part of power converter 200 shown in FIG. 1, description is not repeated here.

  For example, a shielded cable may be used as the power line cable 300. In that case, when the power line cable 300 is long (for example, several meters or more) and / or when the shielded cable is close to the surrounding GND (GND on the power line cable side) (for example, 1 meter or less), the power line cable and the GND The presence of the parasitic capacitance Cp4 may not be negligible.

  When the parasitic capacitance Cp4 exists, a common mode current can flow from the power line cable 300 to the GND. Therefore, a part of the common mode current flowing through the ground line EL2 flows to the GND on the power line cable side via the parasitic capacitance Cp4 when passing through the power line cable 300. The common mode current flowing through the GND on the power line cable side passes through the GND on the power supply 100 side and returns to the input portion of the power conversion device 200A. Here, the path from the power line side GND to the power source side GND is farther from the power lines POL1 to POL3 than the ground line EL2. Therefore, the common mode currents flowing through the power lines POL1 to POL3 and GND hardly cancel each other, and electromagnetic radiation due to the common mode current is generated.

  Therefore, when the parasitic capacitance Cp4 exists, the common mode current may not be sufficiently reduced only by providing the common mode core 240 for the power lines POL1 to POL3 as shown in FIG.

  Therefore, in power converter 200A according to Embodiment 2, a four-wire common mode core provided for power lines POL1 to POL3 and ground wire EL2 is employed as common mode core 240A. Since the common mode core 240A prevents the common mode current from flowing through the ground line EL2, the common mode current flowing from the ground line EL2 to the GND on the power line cable side via the parasitic capacitance Cp4 can be reduced. As a result, it is possible to reduce the electromagnetic radiation due to the common mode current flowing between the GND on the power line cable side and the GND on the power source side, thereby suppressing the noise of the power conversion device 200A.

[Embodiment 3]
In the second embodiment, the method for further reducing the common mode current from the first embodiment by using the common mode core 240A (FIG. 4) has been described. In contrast, in the third embodiment, a method for further reducing the common mode current by connecting a capacitance element in parallel to the inductance element 260 (FIG. 1) will be described.

  FIG. 5 is a diagram for explaining a power conversion device 200B according to the third embodiment. Referring to FIG. 5, power conversion device 200 </ b> B is different from power conversion device 200 (FIG. 1) in that it includes capacitance element 280. Since the structure of the other part of power converter 200B is the same as that of the corresponding part of power converter 200 shown in FIG. 1, description is not repeated here.

  The capacitance element 280 is connected in parallel with the inductance element 260 between the ground line EL3 and the GND on the power supply 100 side.

  When viewed as a circuit with respect to the portion of the ground line EL2 located in the power line cable 300, the path toward the GND on the power line cable side through the parasitic capacitance Cp4, the ground line EL2, the cooling fin 250, the ground A path toward the GND on the power supply 100 side via the line EL3 and the capacitance element 280 exists in parallel. The common mode current flowing through the ground line EL2 flows through a path toward the GND on the power supply 100 side via the capacitance element 280, thereby reducing the common mode current flowing to the GND on the power line cable side via the parasitic capacitance Cp4. it can. Thereby, the electromagnetic radiation by the common mode current flowing between the GND on the power line cable side and the GND on the power source 100 side can be reduced.

  The capacitance of the capacitance element 280 is set to the combined capacity of the capacitors C1 to C3 so that the common mode current fed back to the power conversion device 200B via the capacitors C1 to C3 does not flow to the GND on the power supply 100 side by the capacitance element 280. Should be smaller.

  Specifically, the capacitances of the capacitors C1 to C3 that are the ground capacitors are, for example, about several tens of nF. In that case, the capacitance of the capacitance element 280 is preferably about several nF at the maximum. When the capacitance of the capacitance element 280 is larger than several nF, a common mode current having a frequency component of, for example, about 150 kHz to 30 MHz easily passes through the capacitance element 280, and the power converter 200B has a capacitor C1 to C3. This is because it is difficult to return to the input portion.

  More specifically, for example, it is assumed that the capacitances of the capacitors C1 to C3 are 10 nF. In that case, the combined capacitance of the capacitors C1 to C3 with respect to the common mode current is 30 nF. On the other hand, if the inductance value of the parasitic inductance in the wiring of the capacitors C1 to C3 is 10 nH, the resonance frequency of the capacitors C1 to C3 is about 9 MHz (resonance frequency = 1 / (2π√LC)). At a frequency higher than the resonance frequency, the capacitors C1 to C3 exhibit inductivity instead of capacitance, so that it is difficult to function as a ground capacitor. Further, as the frequency increases from the resonance frequency, the functions of the capacitors C1 to C3 as the ground capacitors are reduced.

  On the other hand, if the capacitance element 280 has a capacitance value of several nF or less, the capacitance can be maintained even at a frequency of 30 MHz. Therefore, even a common mode current having a frequency component of 30 MHz or higher can be returned to the input portion of the power conversion device 200B via the capacitors C1 to C3.

  As mentioned above, although embodiment of this invention was described, combining the characteristic part of each embodiment mentioned above suitably is planned from the beginning. The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiment but by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

  100 power supply, 200, 200A, 200B, 200E power converter, 210 substrate, 220 rectifier circuit, 230 inverter circuit, 240, 240A common mode core, 250 cooling fin, 251 notch, 260 inductance element, 270 insulating member, 280 capacitance Element, 300 power line cable, 400 load, 410 housing, BL magnetic flux, C1-C4 capacitor, Cp1-Cp4 parasitic capacitance, D1-D6 diode, EL1-EL3 (EL) ground wire, N1-N3 input node, Na-Nc Output node, P1, P2, P3, P4 path, PIL1 to PIL3, POL1 to POL3 power line, S substrate surface, SW1 to SW6 switching element, T1 to T3, TE terminals.

Claims (5)

A power conversion device that converts power from a power source and supplies it to a load,
The power source is connected to the ground on the power source side,
The load is housed in a housing to which a ground wire is connected,
The power converter is
A ground capacitor having one end connected to the input portion of the power converter and the other end connected to the ground wire;
A common mode core provided for a power line connecting the output portion of the power converter and the load;
A power converter comprising: the ground wire and an inductance element connected between the ground on the power supply side. A cooling fin having a notch,
The power converter according to claim 1, wherein the inductance element is disposed in the notch. Further comprising a substrate on which the ground capacitor is mounted,
The power conversion device according to claim 1, wherein the inductance element is arranged so that a magnetic flux direction of the inductance element and a surface direction of the substrate are parallel to each other.   The power conversion device according to claim 1, wherein the common mode core is provided for the power line and the ground line.   The power conversion device according to claim 1, further comprising a capacitance element connected in parallel to the inductance element.

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