JP4496896B2 - Power converter - Google Patents

Description

  The present invention relates to a power converter, and more particularly to a power converter that is connected to a positive bus and a negative bus by a bus bar and receives a DC voltage.

  In a power conversion device such as an inverter, a configuration is known in which positive and negative electrodes of a DC power source such as a battery are connected to each switching element with a bus bar (for example, Patent Document 1).

In particular, in the voltage conversion device disclosed in Patent Document 1, a compact structure is realized by arranging a bus bar above a circuit block in which a switching element is arranged.
JP 2003-116276 A

  However, in the bus bar arrangement as in Patent Document 1, since the bus bar and a part of the substrate overlap each other when viewed from the direction perpendicular to the substrate surface, the current flowing on the substrate is affected by the electromagnetic field generated by the current passing through the bus bar. There is a possibility that a region where the amount of heat generation locally increases due to power concentration is generated.

  As is well known, when the temperature rise of the semiconductor switching element is significant, it leads to element breakdown failure, and it is necessary to avoid such local current concentration.

  The present invention has been made to solve such problems, and the object of the present invention is to overlap a part of the substrate when viewed from the direction perpendicular to the substrate on which the semiconductor switching element is mounted. It is an object of the present invention to provide an arrangement layout that prevents local current concentration on a substrate due to an electromagnetic field from a bus bar in a power conversion device in which a bus bar is arranged.

  A power converter according to the present invention is a power converter that receives a DC voltage from a positive bus and a negative bus, and includes a plurality of semiconductor switching elements, a first bus bar, a second bus bar, and an output conductor. Prepare. The plurality of semiconductor switching elements perform switching control for power conversion. The first bus bar is formed of a conductor and electrically connects the positive bus and the plurality of semiconductor switching elements. The second bus bar is formed of a conductor and electrically connects the negative bus and the plurality of semiconductor switching elements. The output conductor is electrically connected to the first and second bus bars via a plurality of semiconductor switching elements, and is provided for taking out a passing current of the plurality of switching elements. The first and second bus bars face a part of the substrate surface so as to be vertically separated from the substrate surface and overlap each other when viewed from the vertical direction with respect to the substrate on which the plurality of switching elements are mounted. Stacked. Further, which one of the first and second bus bars is arranged closer to the substrate is determined by flowing through a plurality of current paths formed between the first and second bus bars and the output conductor on the substrate. Of the current, the angle formed by the current having the maximum parallel component with the first and second bus bars and the passing current of the bus bar arranged on the side close to the substrate is in the range of 90 to 270 degrees. Designed as such.

  In the above power conversion device, the parallel component of the current having the largest bus bar parallel component out of the current flowing through the substrate and the passing current of the bus bar closer to the substrate are in opposite directions. Electromagnetic force acts in a direction away from directly below the bus bar. For this reason, current concentration near the vicinity of the bus bar is unlikely to occur, and temperature increase in a specific switching element due to local current concentration on the substrate can be prevented.

  As a result, it is possible to prevent a problem from occurring in protection of the switching element. Moreover, since the output restriction | limiting etc. accompanying element temperature rise can also be prevented, the output power level from a power converter device can be ensured.

  Preferably, in the power conversion device according to the present invention, the second bus bar has an extraction tab portion electrically connected to the negative electrode conductor formed on the substrate surface, and the extraction tab portion is connected to the extraction tab portion. 2 has a shape in which an angle formed between an inflow current to the body portion of the bus bar and a passing current of the body portion is 90 degrees or less.

  In the said power converter device, it can prevent that the inflow current to the 2nd bus bar (N bus bar) via an extraction tab part turns into an annular current. Therefore, it is possible to prevent the occurrence of a magnetic field in the direction perpendicular to the substrate that generates an eddy current on the surface of the substrate by generating an annular current in the extraction tab portion. As a result, it is possible to prevent the temperature increase in the specific switching element due to local current concentration on the substrate, and to realize the protection of the switching element and the securing of the output power level from the power converter.

  More preferably, in the power conversion device according to the present invention, one of the first and second bus bars arranged on the side closer to the substrate has an electromagnetic field acting on the substrate from the other of the first and second bus bars. Made of magnetic material to damp.

  In the power converter, the electromagnetic field can be weakened from the other bus bar far from the substrate on the substrate surface by the magnetic field attenuation action of the one bus bar closer to the substrate. Therefore, by reducing the electromagnetic force due to the magnetic field from the bus bar that acts on the current flowing on the substrate, the occurrence of a temperature rise in a specific switching element due to local current concentration on the substrate can be prevented, and the switching element Protection of output power and securing of output power level from the power converter.

  A power converter according to another configuration of the present invention is a power converter that receives a DC voltage from a positive bus and a negative bus, and includes a plurality of semiconductor switching elements, a first bus bar, a second bus bar, An output conductor and magnetic field attenuation means are provided. The plurality of semiconductor switching elements perform switching control for power conversion. The first bus bar is formed of a conductor and electrically connects the positive bus and the plurality of semiconductor switching elements. The second bus bar is formed of a conductor and electrically connects the negative bus and the plurality of semiconductor switching elements. The output conductor is electrically connected to the first and second bus bars via a plurality of semiconductor switching elements, and is provided for taking out a passing current of the plurality of switching elements. The magnetic field attenuating means is provided between the first and second bus bars and the substrate, and attenuates an electromagnetic field generated by a passing current of the first and second bus bars.

  In the power converter, the electromagnetic field due to the current passing through the bus bar acting on the substrate surface can be weakened by the magnetic field attenuating means. Therefore, by reducing the electromagnetic force due to the electromagnetic field from the bus bar acting on the current flowing on the substrate, the occurrence of temperature rise at a specific switching element due to local current concentration on the substrate can be prevented and switching can be performed. It is possible to realize protection of the element and securing of the output power level from the power conversion device.

  Preferably, in the power conversion device according to another configuration of the present invention, the magnetic field attenuation means includes a magnetic circuit formed of a magnetic material so as to surround the first and second bus bars.

  Preferably, in the power conversion device according to another configuration of the present invention, the magnetic field attenuating means includes a magnetic shielding plate made of a plate-like magnetic material disposed between the first and second bus bars and the substrate. Including.

  Alternatively, preferably, the magnetic field attenuation means includes a magnetic circuit formed of a magnetic material so as to surround the substrate.

  In the above power converter, since the electromagnetic field from the bus bar can be attenuated by the magnetic shielding structure of the magnetic material, the magnetic field can be sufficiently attenuated even if the distance between the bus bar and the substrate is short. As a result, in the power conversion device in which the bus bar is arranged so as to overlap the substrate plane in the direction perpendicular to the substrate surface, the size in the substrate vertical direction can be reduced.

  In the power conversion device according to the present invention, the bus bar is disposed so as to overlap with a part of the substrate when viewed from the vertical direction with respect to the substrate on which the semiconductor switching element is mounted. It is possible to provide an arrangement layout that prevents local current concentration on the substrate due to the field.

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

[Embodiment 1]
FIG. 1 is a circuit diagram illustrating a configuration of a power conversion device 10 having a bus bar arrangement structure according to an embodiment of the present invention.

  Referring to FIG. 1, a power conversion apparatus 10 according to an embodiment of the present invention includes a DC power supply 20, a smoothing capacitor 30, a control circuit 40, a signal generation circuit 50, and an inverter 100a for driving a rotating machine M1. And an inverter 100b for driving the rotating machine M2.

  The DC power supply 20 is configured by a battery or a combination of a battery and a converter that converts an output voltage level of the battery, and outputs a DC voltage.

  The positive electrode of DC power supply 20 is connected to positive bus 21. On the other hand, the negative electrode of the DC power supply 20 is connected to the negative bus 22 corresponding to the ground wiring. A smoothing capacitor 30 is connected between the positive bus 21 and the negative bus 22 for removing a ripple component of the DC voltage between them.

  Rotating machines M1 and M2 are configured by a three-phase AC synchronous motor, a three-phase induction rotating machine, or the like, and receive AC power from inverters 100a and 100b, respectively, to generate a rotational driving force. The rotating machines M1 and M2 are also used as generators, and the electric power generated by the power generation action (regenerative power generation) at the time of deceleration is converted into a DC voltage by the inverters 100a and 100b, and is smoothed by the smoothing capacitor 30 and DC. The battery (secondary battery) in the power source 20 can be used for charging.

  Inverter 100a is a three-phase inverter composed of power semiconductor switching elements (hereinafter simply referred to as switching elements) Q1a to Q6a. Similarly, inverter 100b is a three-phase inverter constituted by power semiconductor switching elements (hereinafter simply referred to as switching elements) Q1b to Q6b.

  In the embodiment of the present invention, the switching element is composed of, for example, an IGBT (Insulated Gate Bipolar Transistor), but other power semiconductor switching elements such as a bipolar transistor and a MOS transistor can also be used.

  Inverter 100a includes U-phase arm 102a, V-phase arm 104a and W-phase arm 106a connected in parallel between positive bus 21 and negative bus 22. U-phase arm 102a includes switching elements Q1a and Q2a connected in series between positive bus 21 and negative bus 22. Similarly, V-phase arm 104a is formed of switching elements Q3a and Q4a connected in series between positive bus 21 and negative bus 22, and W-phase arm 106a is connected to positive bus 21 and negative bus 22. It is composed of switching elements Q5a and Q6a connected in series between them.

  In each phase arm, a connection point between the switching elements of the upper arm and the lower arm connected in series is connected to each phase end of each phase coil of the rotating machine M1. Specifically, the connection point of U-phase arm 102a is connected to one end of the U-phase coil by output bus bar 172a. Similarly, the connection point of V-phase arm 104a is connected to one end of the W-phase coil by output bus bar 174a, and the connection point of W-phase arm 106a is connected to one end of the W-phase coil by output bus bar 176a. The other end of each phase coil of the rotating machine M1 is electrically connected to each other at a neutral point N1.

  The output bus bars 172a, 174a, 174a take out the passing currents of the switching elements Q1a to Q6a as the respective phase currents and transmit them to the respective phase coils of the rotating machine M1. The output bus bars 172a, 174a, 176a are provided with a current sensor 118a, and each detected phase current is sent to the control circuit 40.

  Drive circuits 111a to 116a are provided corresponding to switching elements Q1a to Q6a, respectively. Drive circuits 111a to 116a control on / off of corresponding switching elements Q1a to Q6a in response to switching control signals S1a to S6a generated by signal generation circuit 50, respectively. Further, anti-parallel diodes D1a to D6a for passing a reverse current are provided in parallel with switching elements Q1a to Q6a, respectively.

  Inverter 100b has the same configuration as inverter 100a, and includes U-phase arm 102b composed of switching elements Q1b and Q2b, W-phase arm 104b composed of switching elements Q3b and Q4b, and switching elements Q5b and Q6b. W-phase arm 106b configured.

  U-phase arm 102b, W-phase arm 104b and W-phase arm 106b are connected to one end of each phase coil of rotating machine M2 by output bus bars 172b, 174b, and 176b. The other ends of the phase coils of the rotating machine M2 are electrically connected to each other at a neutral point N2. Further, the output bus bars 172b, 174b, and 176b are provided with a current sensor 118b, and each detected phase current is sent to the control circuit 40.

  Drive circuits 111b to 116b are provided corresponding to switching elements Q1b to Q6b, respectively. Drive circuits 111b to 116b control on / off of corresponding switching elements Q1b to Q6b in response to switching control signals S1b to S6b generated by signal generation circuit 50, respectively. Further, antiparallel diodes D1b to D6b are provided in parallel with switching elements Q1b to Q6b, respectively.

  Control circuit 40 controls the operation of DC power supply 20 and inverters 100a and 100b. Specifically, the control circuit 40 receives the torque command values of the rotating machines M1 and M2, the current values of the respective phases, and the input voltage to the inverters 100a and 100b (that is, the output voltage of the DC power supply 20) as inputs, and the rotating machine M1. , M2 is applied to each phase coil based on the well-known PWM (Pulse Width Modulation) control or the like, and the calculation result is output to the signal generation circuit 50.

  The signal generation circuit 50 receives the voltage calculation result of each phase coil from the control circuit 40, and controls switching control signals S1a to S6a, which are PWM control signals for controlling on / off of the switching elements Q1a to Q6a, Q1b to Q6b, and S1b to S6b are generated. The switching control signals S1a to S6a are sent to the driver circuits 111a to 116a, respectively, and the switching control signals S1b to S6b are sent to the driver circuits 111b to 116b, respectively.

  When the DC power supply 20 includes a converter (not shown) and its output voltage level can be changed, the output voltage from the DC power supply 20 depends on the operating range of the rotating machines M1 and M2. The operation of the converter is controlled so that becomes the optimum level. Specifically, the control circuit 40 calculates the optimum value (target value) of the input voltages of the inverters 100a and 100b, using the above-described torque command value and motor rotation speed as inputs. Further, the control circuit 40 generates a control signal for instructing the switching operation of the converter necessary for obtaining this input voltage, that is, the output voltage of the DC power supply 20.

  FIG. 2 is a diagram illustrating the layout on the substrate of the switching elements and antiparallel diodes that constitute inverters 100a and 100b. FIG. 2 shows a plan layout diagram of a substrate 300 on which these switching elements and antiparallel diodes are mounted.

  Referring to FIG. 2, substrate 300 includes positive conductors 182a, 184a, 186a, 182b, 184b, 186b connected to positive bus 21 by a positive bus bar (P bus bar) described in detail later, and negative bus bars ( Negative conductors 192a, 194a, 196a, 192b, 194b, 196b and output conductors 202a, 204a, 206a, 202b, 204b, 206b connected to the negative bus 22 by N bus bars) are provided. The output conductors 202a, 204a, 206a, 202b, 204b, and 206b are electrically connected to the output bus bars 172a, 174a, 176a, 172b, 174b, and 176b shown in FIG.

  Each positive conductor, each negative conductor, and each output conductor are electrode plates made of, for example, copper, and are provided on the main surface of the substrate 300 on an insulating layer (not shown).

  Each switching element constituting inverters 100a and 100b is formed of a plurality of transistor units connected in parallel.

  For example, switching element Q1a arranged in U-phase arm 102a of inverter 100a is realized by parallel connection of three transistor units Q11a to Q13a. The other switching elements Q2a to Q6a of the inverter 100a are also realized by parallel connection of three transistor units Q21a to Q23a, Q31a to Q33a, Q41a to Q43a, Q51a to Q53a, and Q61a to Q63a, respectively.

  The switching elements Q1b to Q6b of the inverter 100b are realized by parallel connection of two transistor units Q21b to Q22a, Q31b to Q32b, Q41b to Q42b, Q51b to Q52b, and Q61b to Q62b, respectively.

  Similarly, the antiparallel diodes D1a to D6a of the inverter 100a are realized by parallel connection of three diode units D11a to D13a, D21a to D23a, D31a to D33a, D41a to D43a, D51a to D53a, and D61a to D63a. . Further, the antiparallel diodes D1b to D6b of the inverter 100b are realized by parallel connection of two diode units D11b to D12b, D21b to D22b, D31b to D32b, D41b to D42b, D51b to D52b, and D61b to D62b.

  The number of transistor units and diode units constituting each switching element and each antiparallel diode in each inverter is designed according to the output current (power) of the inverter.

  In each of inverters 100a and 100b, each phase arm is mounted using a set of one output conductor, one negative conductor, and one positive conductor. Each output conductor has a concave shape, and is arranged adjacent to the positive electrode conductor so that the concave portion is planarly opposed to the corresponding positive electrode conductor. Further, a transistor unit for forming a switching element and an anti-parallel diode constituting the arm using the upper regions of the output conductor and the negative electrode conductor, which are arranged adjacent to each other so that each negative electrode conductor fits in the concave portion of the corresponding output conductor. And a diode unit is arranged. Thus, the inverters 100a and 100b can be laid out on the substrate 300 in a compact manner.

  For example, the upper arm of U-phase arm 102a of transistor circuit 100a will be described. Transistor units Q11a to Q13a and corresponding diode units D11a to D13a are mounted on positive conductor 182a and are electrically connected to positive conductor 182a. . Further, the transistor units Q11a to Q13a and the diode units D11a to D13a are electrically connected to the output conductor 202a by bonding wires 210 to 212. Thus, the transistor units Q11a to Q13a are connected in parallel between the positive conductor 182a and the output conductor 202a, and constitute the switching element Q1a in FIG. Similarly, the diode units D11a to D13a are also electrically connected in parallel between the positive conductor 182a and the output conductor 202a to constitute the antiparallel diode D1a shown in FIG.

  In the lower arm of U-phase arm 102a, transistor units Q21a to Q23a and corresponding diode units D21a to D23a are mounted on output conductor 202a and electrically connected to output conductor 202a. Furthermore, the transistor units Q21a to Q23a and the corresponding diode units D21a to D23a are electrically connected to the negative conductor 192a by bonding wires 213 to 215. Thus, the transistor units Q21a to Q23a are connected in parallel between the negative electrode conductor 192a and the output conductor 202a, and constitute the switching element Q2a in FIG. Similarly, the diode units D21a to D23a are also electrically connected in parallel between the negative electrode conductor 192a and the output conductor 202a to constitute the antiparallel diode D2a shown in FIG.

  The V-phase arm 104a and the W-phase arm 106a of the inverter 100a also follow the same layout as the U-phase arm 102a, and use the bonding wires 220 to 225 and 230 to 235 to form transistor units Q31a to Q33a and Q51a that constitute the upper arm. -Q53a and diode units D31a-D33a, D51a-D53a, and transistor units Q41a-Q43a, Q61a-Q63a and diode units D41a-D43a, D61a-D63a constituting the lower arm are positive conductors 184a, 186a and output conductors 204a , 206a.

  Further, for each phase arm 102b, 104b, 106b of inverter 100b, transistor units Q11b-Q12b that constitute the upper arm using bonding wires 216-219, 226-229, 236-239 in accordance with the same layout as described above. , Q31b to Q32b, Q51b to Q53b and diode units D11b to D12b, D31b to D32b, D51b to D52b, and transistor units Q21b to Q22b, Q41b to Q42b, Q61b to Q62b, and diode units D21b to D22b constituting the lower arm, D41b to D42b and D61b to D62b are mounted on the positive conductors 182b, 184b and 186b and the output conductors 202b, 204b and 206b.

  Next, the arrangement of the bus bars with respect to each positive electrode conductor, each negative electrode conductor, and each output conductor and problems thereof will be described.

  3 and 4 are diagrams for explaining the arrangement of bus bars shown as a comparative example of the present invention.

  Referring to the plan view shown in FIG. 3, P bus bar (positive bus bar) 150 and N bus bar (negative bus bar) 160 are provided in common to inverters 100a and 100b. The P bus bar 150 and the N bus bar 160 are provided as wide electrodes wider than a thickness made of, for example, copper.

  The P bus bar 150 includes a body portion 151, a plurality of extraction tabs 152, and a connector portion 153. Connector portion 153 is connected to positive bus 21 shown in FIG. Each extraction tab 152 is provided as a protrusion from the wide body portion 151 corresponding to each of the positive conductors 182a, 184a, 186a, 182b, 184b, and 186b, and is electrically connected to the corresponding positive conductor. Is done. Thereby, each positive electrode conductor on the board | substrate 300 is electrically connected with the positive electrode of the DC power supply 20 shown in FIG.

  Similarly, the N bus bar 160 includes a body portion 161, a plurality of extraction tabs 162, and a connector portion 163. Connector portion 153 is connected to negative side bus 22 shown in FIG. Each extraction tab 162 is provided as a protruding portion from the wide body portion 161 corresponding to each of the negative electrode conductors 192a, 194a, 196a, 192b, 194b, 196b, and is electrically connected to the corresponding negative electrode conductor. Is done. Thereby, each negative electrode conductor on the board | substrate 300 is electrically connected with the negative electrode of the DC power supply 20 shown in FIG.

  The output conductors 202a, 204, 206a are electrically connected to the output bus bars 172a, 174a, 176a, respectively. The output bus bars 172a, 174a, 176a are also provided as wide electrodes having a width wider than that of, for example, copper. As shown in FIG. 1, the output bus bars 172a, 174a, and 176a are further electrically connected to the respective phase coils of the rotating machine M1. Although not shown, output bus bars are similarly provided for the output conductors 202b, 204b, and 206b of the inverter 100b.

  Thereby, each output conductor connected to the output bus bar is connected to the P bus bar 150 and the N bus bar 160 via the switching element, and the passing current of the switching element from each output bus bar, that is, the current converted by the switching operation is obtained. Can be taken out.

  In this way, the electrical connection relationship for realizing the electrical circuit configuration shown in FIG. 1 is realized for each switching element and antiparallel diode via the P bus bar 150, the N bus bar 160, and the output bus bar.

  Here, the influence of the electromagnetic field caused by the current flowing through the bus bar on the current flowing on the substrate 300 will be described using the V-phase arm of the inverter 100a as an example.

  If the influence of the electromagnetic field from the P bus bar 150 and the N bus bar 160 is ignored, the current path I1 from the P bus bar 150 to the output conductor 204a is connected to the output bus bar 174a and the output conductor from the connection point of the extraction tab 152 and the positive conductor 184a. It is formed toward the connection point 204a. The outflow current to the current path I1 is branched from the bus bar current Ip flowing through the body portion 151.

  Similarly, the current path I2 from the output conductor 204a to the N bus bar 160 is formed from the connection point of the output bus bar 174a and the output conductor 204a toward the connection point of the extraction tab 162 and the negative conductor 194a. The inflow current to the extraction tab 162 passes through the current path I3 and merges with the bus bar current In flowing through the body portion 161. The bus bar current In flows in a direction toward the connector portion 163, and the bus bar current Ip flows in a direction opposite to the bus bar current In.

  As shown in FIG. 4 corresponding to the IV-IV cross-sectional view in FIG. 3, the P bus bar 150 and the N bus bar 160 are arranged on the side close to the substrate 300 (lower side). The N bus bar 160 is arranged on the side (upper side) farther than the substrate 300.

  Referring to FIG. 4, the electromagnetic fields cancel each other at a portion where both bus bar current Ip and bus bar current In flow, but the electromagnetic fields remain without being canceled at other portions. The portion where such an electromagnetic field is canceled and the remaining portion vary depending on the on / off pattern of the switching element.

  As described above, in the portion where only one bus bar current flows, the currents on the current paths I1 and I2 on the substrate 300 are affected by the influence of the electromagnetic field due to the bus bar current. The electromagnetic field due to the bus bar current exerts an electromagnetic force on the current component parallel to the bus bar.

  As shown in FIG. 3, depending on the layout of the positive electrode conductor, the negative electrode conductor, and the output conductor on the substrate 300 (FIG. 2), the current in the current path I1 is less in the bus bar parallel component than the current in the current path I2. growing. In addition, since the P bus bar 150 is closer to the substrate 300, the influence of the electromagnetic field from the bus bar current on the current on the substrate is that the bus bar current Ip of the lower P bus bar and the current having the largest bus bar parallel component. It becomes the maximum between the passing current of the path I1.

  Referring to FIG. 4 again, according to the bus bar arrangement of the comparative example, the bus bar current Ip on the side closer to the substrate and the bus bar parallel component of the current flowing through the current path I1 are in the same direction, so an attractive force acts between them. It will be. As a result, the electromagnetic force F attracted in the direction directly below the bus bar acts on the current on the current path I1. For this reason, the current concentrates on the transistor unit Q (generally showing the transistor units on the substrate, the same applies hereinafter) arranged near the bus bar, which may cause a temperature rise.

  FIG. 5 is a simulation example in which current concentration due to the bus bar arrangement of the comparative example is analyzed.

  In FIG. 5, the simulation result of the current density in the bus bar arrangement of the comparative example shown in FIG. 3 is shown in gray scale. Grayscale shading indicates the current density level (dark: high density, light: low density).

  As shown in FIG. 5, it can be seen that current concentration occurs in the vicinity of the bus bar arrangement region due to the electromagnetic force that the magnetic field caused by the bus bar current acts on the passing current on the substrate. As a result, for example, the transistor unit Q11a, Q23a, Q43a, Q51a is concerned about an increase in temperature.

  Further, the inflow current in the take-out tab 162 of the N bus bar 160 may cause a current concentration problem.

  Referring to FIG. 3 again, the current path I3 of the inflow current from the N bus bar take-out tab 162 to the body portion 161 is formed so as to wrap around in an annular shape. That is, the angle formed between the current flowing into the extraction tab 162 and the bus bar current In is greater than 90 degrees and about 180 degrees.

  In this manner, an annular portion is formed by the extraction tab 162, and when a clockwise current flows through the annular portion, a downward magnetic field 310 is generated as shown in FIG. 6 which is a VI-VI sectional view in FIG. appear.

  Due to this downward magnetic field 310, an eddy current is generated in the region immediately below the extraction tab 162, and current concentration may occur in the transistor unit Q disposed in the vicinity.

  As described above, in the bus bar arrangement shown as the comparative example in FIGS. 3 and 4, current concentration is likely to occur in the region directly below the bus bar on the substrate 300, and there is a problem in protection of the switching element due to local temperature rise. It can happen.

  Next, the bus bar arrangement according to the first embodiment of the present invention that solves the above problems will be described.

  FIG. 7 is a plan view for explaining an example of bus bar arrangement according to Embodiment 1 of the present invention.

  Referring to FIG. 7, also in the configuration according to the first embodiment, P bus bar 150 and N bus bar 160 are provided in common to inverters 100a and 100b, and are perpendicular to substrate 300 with respect to the substrate surface. Are stacked so as to face a part of the substrate surface so as to overlap each other when viewed from the vertical direction.

  Note that, as shown in FIG. 8 corresponding to the VIII-VIII cross-sectional view in FIG. 7, the N bus bar 160 is arranged on the side (lower side) close to the substrate 300, and the P bus bar 150 is on the side farther from the substrate 300 (upper side). ).

  Furthermore, in the configuration according to the first embodiment, the shapes of the extraction tabs 152 and 162 for the P bus bar 150 and the N bus bar 160 are different from the comparative example shown in FIG. That is, the shapes of the body portion 151 and the connector portion 153 of the P bus bar 150 and the shapes of the body portion 161 and the connector portion 163 of the N bus bar 160 are the same as those shown in FIG.

  The layout of each switching element (transistor unit) and diode element (diode unit) on the substrate 300 is the same as that described with reference to FIG.

  As shown in FIG. 7, the bus bar current passing through the body portion of the lower bus bar directly facing the substrate 300, that is, the N bus bar 160, is exchanged with the comparative example shown in FIG. The angle θ0 formed by In and the current on the current path I1 having a large bus bar parallel component on the substrate 300 is designed to be in the range of 90 ° to 270 °.

  Conversely, in the comparative example shown in FIG. 3, since the bus bar current Ip of the lower bus bar and the bus bar parallel component of the current on the current path I1 are in the same direction, the angle θ0 is ± 90 degrees. That is, it is in the range of 0 ° to 90 ° or 270 ° to 360 °.

  As shown in FIG. 8, the N bus bar 160 is arranged on the lower surface, and the angle θ0 shown in FIG. 7 is set in the range of 90 ° to 270 °, so that the bus bar parallel component of the current on the current path I1 is Since the direction is opposite to the bus bar current In close to the substrate 300, a repulsive force acts between them. As a result, the electromagnetic force F # acts on the current on the current path I1 in a direction away from directly below the bus bar. For this reason, current concentration on the transistor unit Q (generally showing transistor units on the substrate, the same applies hereinafter) arranged near the bus bar is less likely to occur, and concentration of the current on the substrate immediately below the bus bar is prevented. It becomes possible. Therefore, it is possible to prevent an increase in temperature in a specific transistor unit (switching element) due to local current concentration.

  Further, the N bus bar 160 on the side close to the substrate 300 (the lower side) is made of a magnetic material having a high permeability such as permalloy, thereby shielding the electromagnetic field caused by the P bus bar current Ip of the P bus bar 150, thereby increasing the current on the substrate. The force acting on can be suppressed.

  Further, as shown in FIG. 9, by changing the shape of the mounting tab 162, the angle θ1 formed by the bus bar current In flowing through the body portion 161 of the N bus bar 160 and the current path I3 flowing in from the mounting tab 162 is 90 degrees or less. It has become. Therefore, as in the comparative example shown in FIG. 3, it is possible to prevent the annular inflow current from being generated in the mounting tab 162, thereby preventing the downward magnetic field 310 shown in FIG. 6 from being generated. Thereby, current concentration on the substrate due to the cause described in FIG. 6 is less likely to occur.

  As a result, local current concentration of each transistor unit (switching element) and diode unit (diode element) mounted on the substrate 300 can be avoided. Thereby, in inverter 100a, 100b, it can prevent that the temperature of a specific switching element rises and a problem arises in element protection. In addition, since output restriction or the like associated with an increase in element temperature can be prevented, the output power level from inverters 100a and 100b can be secured.

  FIG. 10 is a plan view illustrating another bus bar arrangement example according to Embodiment 1 of the present invention.

  The bus bar arrangement example shown in FIG. 10 differs from the arrangement example shown in FIG. 7 in the shapes of the extraction tabs 152 and 162. On the other hand, the positional relationship between P bus bar 150 and N bus bar 160 and the layout on substrate 300 are the same as in the example shown in FIG. 7, and therefore detailed description will not be repeated.

  In the arrangement example shown in FIG. 10, the extraction tab 152 of the P bus bar 150 is formed in a shape having a curved portion, and the extraction tab 162 of the N bus bar 160 is provided in a linear shape.

  Even if the extraction tab 152 of the P bus bar 150 has such a curved shape, the angle θ0 formed by the current path I1 from each extraction tab 152 to each output conductor and the adjacent lower bus bar current In is shown in FIG. Similar to the configuration example, the range is 90 to 270 degrees.

  Furthermore, as shown in FIG. 11, the angle θ1 formed by the inflow current (current path I3) in the take-out tab 162 of the N bus bar 160 and the bus bar current In of the body portion 161 is 90 °, which is shown in FIG. Similar to the configuration example, the condition of θ1 ≦ 90 ° can be satisfied.

  For this reason, since no annular current is generated in the extraction tab 162, current concentration on the substrate due to the downward magnetic field 310 shown in FIG. 6 is less likely to occur as in the arrangement example shown in FIG.

  As described above, the bus bar arrangement example shown in FIG. 10 also avoids current concentration on the substrate 300, and each transistor unit (switching element) and diode unit (diode element), as in the arrangement example shown in FIG. ) Local current concentration can be avoided. A local temperature rise can be avoided.

  As described above, in the bus bar arrangement according to the first embodiment of the present invention, the angle θ 0 formed between the lower bus bar current and the current having the largest bus bar parallel component on the current path on the substrate, and The shape and arrangement of the bus bars are designed in consideration of the angle θ1 formed by the current flowing into the N bus bar 160 and the bus bar current In.

  7 and FIG. 10 is based on the layout on the substrate 300 shown in FIG. 2, the N bus bar 160 is closer to the substrate 300 in order to set the angle θ0 within the above range ( (Lower side). However, the P bus bar 150 and the N bus bar 160 are not limited to such a case. That is, depending on the layout on the substrate 300, a configuration in which the P bus bar 150 is disposed on the lower side in consideration of the angle θ1 with respect to the current at which the bus bar parallel component is maximum is also employed.

[Embodiment 2]
In the second embodiment, a configuration for avoiding current concentration on the substrate by providing a magnetic field attenuation structure between the bus bar and the substrate will be described with reference to FIGS. 12 to 15 show the cross-sectional structure of the bus bar arrangement as in FIG.

  As shown in FIG. 12, in the first example of the second embodiment, a magnetic circuit 400 made of a high-permeability magnetic material such as permalloy so as to surround the P bus bars 150 and 160 is used as the magnetic field attenuation structure. Provide.

  The magnetic circuit 400 shields the electromagnetic field from the P bus bar 150 and the N bus bar 160, and the magnetic field on the substrate 300 is attenuated. Thereby, since the electromagnetic force acting on the current on the substrate 300 is weakened, current concentration occurs in a specific transistor unit (that is, the switching element) on the substrate 300 by the action of the electromagnetic force due to the magnetic field from the bus bar, Local temperature rise can be prevented from occurring.

  Alternatively, as in the second example shown in FIG. 13, a magnetic shielding plate 410 made of a high permeability magnetic material such as permalloy is disposed between the P bus bar 150 and the N bus bar 160 and the substrate 300. This also makes it possible to obtain the same operations and effects as the configuration example shown in FIG.

  Further, as in the third example shown in FIG. 14, a magnetic circuit 420 made of a magnetic material having a high magnetic permeability may be provided on the substrate 300 side so as to surround at least the transistor unit Q (switching element). . The magnetic circuit 420 can also attenuate the electromagnetic fields from the P bus bar 150 and the N bus bar 160 that act on the substrate 300, so that the same effect as the configuration example shown in FIG. 12 can be obtained.

  Alternatively, as shown in FIG. 15, by providing a sufficient distance r between the P bus bar 150 and the N bus bar 160 and the switching element Q on the substrate 300 without providing a magnetic shielding structure made of a magnetic material, It is also possible to weaken the magnetic field due to the bus bar current acting on the. Such a structure can be employed when there is a layout margin in the direction perpendicular to the substrate surface.

  Conversely, in the case of providing a magnetic shielding structure made of a magnetic material as in the examples of FIGS. 12 to 14, the electromagnetic field from the bus bar that acts on the substrate without securing the distance r between the bus bar and the substrate. Therefore, the dimension in the direction perpendicular to the substrate surface can be reduced.

  Note that the magnetic field attenuation structure according to the second embodiment can be applied regardless of the vertical relationship of the arrangement of the P bus bar 150 and the N bus bar 160. In other words, the combination with the bus bar arrangement shown in Embodiment Mode 1 can further reduce the magnetic field from the bus bar acting on the substrate 300. Alternatively, the present invention can be applied independently from the first embodiment, and the magnetic field attenuation structure according to the second embodiment can be used to weaken the magnetic field from the bus bar on the substrate 300, thereby preventing temperature rise due to local current concentration. Good.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a circuit diagram explaining the structure of the power converter device 10 which has the bus-bar arrangement structure by embodiment of this invention. It is a top view explaining the layout on the board | substrate of the switching element and antiparallel diode which comprise inverter 100a, 100b. It is a top view explaining the bus-bar arrangement | positioning shown as a comparative example of this invention. It is sectional drawing explaining the bus-bar arrangement | positioning shown as a comparative example of this invention. It is a figure explaining the simulation result regarding the current concentration on the board | substrate in the comparative example shown in FIG. 3 and FIG. It is a figure explaining the magnetic field which generate | occur | produces with the inflow current in the extraction tab of N bus-bar. It is a top view explaining the example of bus-bar arrangement | positioning by Embodiment 1 of this invention. It is sectional drawing explaining the bus-bar arrangement example by Embodiment 1 of this invention. It is a figure explaining the angle of the inflow current in the extraction tab of the N bus bar shown in FIG. It is a top view explaining the other bus-bar arrangement example by Embodiment 1 of this invention. It is a figure explaining the angle of the inflow current in the extraction tab of the N bus bar shown in FIG. It is a figure explaining the 1st example of the magnetic damping structure by Embodiment 2. FIG. It is a figure explaining the 2nd example of the magnetic damping structure by Embodiment 2. FIG. It is a figure explaining the 3rd example of the magnetic damping structure by Embodiment 2. FIG. It is a figure explaining the 4th example of the magnetic damping structure by Embodiment 2. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Power converter, 20 DC power supply, 21 Positive side bus, 21 Positive side bus, 22 Negative side bus, 30 Smoothing capacitor, 40 Control circuit, 50 Signal generation circuit, 100a, 100b Inverter, 102a, 102b U-phase arm, 104a , 104b V-phase arm, 106a, 106b W-phase arm, 111a-116a, 111b-116b Driver circuit, 118a, 118b Current sensor, 150 P bus bar (positive bus bar), 151 Body (P bus bar), 152 Extraction tab (P Bus bar), 153 connector part (P bus bar), 160 P bus bar (negative electrode bus bar), 161 body part (N bus bar), 162 take-out tab (N bus bar), 163 connector part (N bus bar), 172a, 174a, 174a, 172b , 174b, 176 Output bus bar, 182a, 184a, 186a, 182b, 184b, 186b Positive conductor, 192a, 194a, 196a, 192b, 194b, 196b Negative conductor, 202a, 204a, 206a, 202b, 204b, 206b Output conductor, 210-239 Bonding wire , 300 substrate, 310 magnetic field, 400, 420 magnetic circuit, 410 magnetic shielding plate, D1a to D6a, D1b to D6b antiparallel diode, D11a to D13a, D21a to D23a, D31a to D33a, D41a to D43a, D51a to D53a, D61a D63a, D11b to D12b, D21b to D22b, D31b to D32b, D41b to D42b, D51b to D52b, D61b to D62b, diode unit, I1 to I3 current path, In, Ip busbar current (body part), M1, M2 rotating machine, Q1a to Q6a, Q1b to Q6b switching element (power semiconductor switching element), Q, Q11a to Q13a, Q21a to Q23a, Q31a to Q33a, Q41a to Q43a, Q51a Q53a, Q61a to Q63a, Q11b to Q12b, Q21b to Q22b, Q31b to Q32b, Q41b to Q42b, Q51b to Q52b, Q61b to Q62b Transistor units, θ0, θ1 angles (between currents).

Claims (7)

A power converter that receives a DC voltage from a positive bus and a negative bus,
A plurality of semiconductor switching elements that perform switching control for power conversion;
A first bus bar formed of a conductor for electrically connecting the positive bus and the plurality of semiconductor switching elements;
A second bus bar formed of a conductor for electrically connecting the negative bus and the plurality of semiconductor switching elements;
An output conductor for extracting a passing current of the plurality of switching elements electrically connected to the first and second bus bars via the plurality of semiconductor switching elements;
The first and second bus bars are spaced apart from the substrate surface in the vertical direction with respect to the substrate on which the plurality of switching elements are mounted, and overlap each other when viewed from the vertical direction. Laminated to face the part,
Which of the first and second bus bars is arranged on the side closer to the substrate depends on a plurality of currents formed between the first and second bus bars and the output conductor on the substrate. Of the current flowing through the path, the angle formed by the current having the maximum parallel component with the first and second bus bars and the passing current of the bus bar arranged on the side close to the substrate is 90 degrees to 270 degrees A power conversion device designed to be within the range. The second bus bar has an extraction tab portion that is electrically connected to a negative electrode conductor formed on the substrate surface,
The take-out tab portion has a shape such that an angle formed between an inflow current from the take-out tab portion to the body portion of the second bus bar and a passing current of the body portion is 90 degrees or less. The power converter described.   One of the first and second bus bars arranged on the side closer to the substrate is made of a magnetic material so as to attenuate an electromagnetic field acting on the substrate from the other of the first and second bus bars. The power converter of Claim 1 or 2 produced. A power converter that receives a DC voltage from a positive bus and a negative bus,
A plurality of semiconductor switching elements that perform switching control for power conversion;
A first bus bar formed of a conductor for electrically connecting the positive bus and the plurality of semiconductor switching elements;
A second bus bar formed of a conductor for electrically connecting the negative bus and the plurality of semiconductor switching elements;
An output conductor for extracting a passing current of the plurality of switching elements, electrically connected to the first and second bus bars via the plurality of semiconductor switching elements;
And a magnetic field attenuating means provided between the first and second bus bars and the substrate, for attenuating an electromagnetic field generated by a current passing through the first and second bus bars.   The power converter according to claim 4, wherein the magnetic field attenuating unit includes a magnetic circuit formed of a magnetic material so as to surround the first and second bus bars.   5. The power conversion device according to claim 4, wherein the magnetic field attenuating unit includes a magnetic shielding plate made of a plate-like magnetic material and disposed between the first and second bus bars and the substrate.   The power converter according to claim 4, wherein the magnetic field attenuating unit includes a magnetic circuit formed of a magnetic material so as to surround the substrate.