JP2012028605A - Power module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power module having enhanced heat resistant life.SOLUTION: A power module 6 disposed adjacent to a coil 5 wound around a stator 4, and electrically connected to the coil 5 comprises: a first semiconductor element 16a; a first current-carrying member 11 laminated on the first semiconductor element 16a; a second semiconductor element 16b; a second current-carrying member 12 laminated on the second semiconductor element 16b; and a third current-carrying member 13 laminated on the side opposite to the first current-carrying member 11 and the second current-carrying member 12 with sandwiching the first semiconductor element 16a and the second semiconductor element 16b. The third current-carrying member 13 includes a high electric resistance 22 having an electric resistance value higher than that of the third current-carrying member 13 at a position between the first current-carrying member 11 and the second current-carrying member 12 viewed from a lamination direction.

Description

  The present invention relates to a power module.

  Conventionally, an inverter module having a switching element or the like arranged in the vicinity of a motor is disclosed in Patent Document 1.

  In patent document 1, the terminal of a switching element, a circuit pattern, etc. are electrically connected by wire bonding.

JP 2007-116840 A

  In the above invention, in the connection by wire bonding, the inverter module becomes thick due to the wire bonding loop height. On the other hand, instead of the connection by wire bonding, for example, the terminal of the switching element and the circuit pattern can be electrically connected by a single conductor plate.

  However, in this case, eddy current is generated in the conductor plate due to the magnetic flux leaked from the stator, heat is generated due to the eddy current, and the heat resistant life of the bonding material between the switching element and the circuit pattern is reduced, for example. There is a problem that the heat-resistant life of the power module is lowered.

  The present invention has been invented to solve such problems, and has an object to improve the heat-resistant life of the power module.

  A power module according to an aspect of the present invention is a power module that is disposed in the vicinity of a coil wound around a stator and electrically connected to the coil, and is laminated on the first semiconductor element and the first semiconductor element. The first current-carrying member, the second semiconductor element, the second current-carrying member laminated on the second semiconductor element, and the first semiconductor element and the second semiconductor element sandwiching the first semiconductor element A third current-carrying member stacked on the opposite side of the current-carrying member and the second current-carrying member, and the third current-carrying member includes a first current-carrying member and a second current-carrying member when viewed from the stacking direction. A high electrical resistance portion having an electrical resistance value higher than that of the third current-carrying member is provided at a position in between.

  According to the present invention, the heat-resistant life of the power module can be improved by suppressing the amount of heat generated by the power module due to the eddy current.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of an electromechanically integrated rotating electrical machine according to a first embodiment of the present invention. It is the figure which looked at the power module in a 1st embodiment from the axial direction. FIG. 3 is a view as seen from an arrow A in FIG. 2. It is a figure for demonstrating the heat_generation | fever condition in a power module when not using this embodiment. It is a figure for demonstrating the heat_generation | fever condition in a power module when not using this embodiment. It is the figure which looked at the power module in 2nd Embodiment of this invention from the axial direction. It is A arrow directional view of FIG.

  The configuration of the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view of an electromechanically integrated rotating electrical machine in which the power module of this embodiment is provided in the vicinity of a coil of the rotating electrical machine. In FIG. 1, a part of a power module, which will be described later in detail, is omitted for explanation. In addition, although this embodiment demonstrates the power module provided in the coil vicinity of the rotary electric machine, it is not restricted to this, It can apply to the power module which is provided in the coil vicinity and generate | occur | produces an eddy current.

  An electromechanically integrated rotating electrical machine (hereinafter referred to as a motor) 1 includes a shaft 2, a rotor 3 provided coaxially with the shaft 2, and a shaft 2 provided coaxially and provided outside the rotor 3 in the radial direction of the shaft 2. A stator 4, a plurality of coils 5 attached to the stator 4, a plurality of power modules 6 for controlling the current flowing in the coils 5, and a case 7 for fixing and holding the stator 4 and the like.

  The rotor 3 is connected to the shaft 2 and rotates integrally with the shaft 2. In addition, although not shown, a permanent magnet is embedded in the rotor 3.

  The stator 4 is formed by arranging a plurality of stator cores 8 in an annular shape. The stator core 8 includes a yoke portion 9 and a teeth portion 10 that protrudes from the yoke portion 9 to the rotor 3 side.

  The coil 5 is formed by winding an electric wire such as a copper wire around the tooth portion 10.

  The power module 6 will be described with reference to FIGS. FIG. 2 is a view of the power module as viewed from the axial direction. 3 is a view taken in the direction of arrow A in FIG. In FIG. 3, the coil 5 and the tooth part 10 are shown for explanation. The power module 6 is disposed in the vicinity of the coil 5 and is electrically connected to the coil 5. The power module 6 is provided so as to face the end surface of the stator 4 in the axial direction of the shaft 2. That is, the power module 6 is provided so as to extend in the radial direction of the shaft 2. The coil 5 and the power module 6 are provided corresponding to each stator core 8.

  The power module 6 includes an upper arm P electrode (first energization member) 11, a lower arm N electrode (second energization member) 12, and an AC electrode (third energization member) 13.

  The upper arm P electrode 11 is configured by providing a switching element (first semiconductor element) 16a on a flat substrate 15a. The switching element 16a is a transistor 17a and a diode 18a. The transistor 17a and the diode 18a are disposed on the upper arm P electrode 11 along the longitudinal direction of the substrate 15a. In the upper arm P electrode 11, the main current flows along the arrangement direction of the transistor 17a and the diode 18a, that is, the longitudinal direction of the substrate.

  Similarly to the upper arm P electrode 11, the lower arm N electrode 12 is configured by providing a switching element (second semiconductor element) 16b on a flat substrate 15b. The switching element 16b is a transistor 17b and a diode 18b.

  The arrangement of the switching element 16a in the upper arm P electrode 11 and the arrangement of the switching element 16b in the lower arm N electrode 12 are the same. In this embodiment, the transistors 17a and 17b are arranged on the radially outer side, and the diodes on the radially inner side. 18a and 18b are arranged. The upper arm P electrode 11 and the lower arm N electrode 12 are electrically connected to an external power source that is a DC power source.

  The AC electrode 13 is composed of an upper arm electrode 20a and a lower arm electrode 20b that are arranged in parallel, and a connecting electrode 21 that connects the end side of the upper arm electrode 20a and the end side of the lower arm electrode 20b. This is a letter-shaped electrode, for example, a conductor plate such as a copper plate. An air layer 22 is formed between the upper arm electrode 20a and the lower arm electrode 20b. The air layer 22 has a larger electric resistance than the upper arm electrode 20a, the lower arm electrode 20b, and the connecting electrode 21, and functions as a high electric resistance portion.

  The AC electrode 13 is stacked on the upper arm P electrode 11 and the lower arm N electrode 12 along the axial direction of the shaft 2. The AC electrode 13 is stacked on the opposite side of the substrate 15a of the upper arm P electrode 11 and the substrate 15b of the lower arm N electrode 12 with the switching elements 16a and 16b interposed therebetween. When viewed from the axial direction of the shaft 2, the AC electrode 13 is disposed so that the upper arm electrode 20 a overlaps the upper arm P electrode 11 and the lower arm electrode 20 b overlaps the lower arm N electrode 12. That is, when the power module 6 is viewed from the axial direction of the shaft 2, the air layer 22 is formed at a position between the upper arm P electrode 11 and the lower arm N electrode. The AC electrode 13 is disposed so that the position of the air layer 22 is within a predetermined positional deviation range in the axial direction and the radial direction of the shaft 2.

  The upper arm electrode 20a is joined to the switching element 16a of the upper arm P electrode 11 by a paste material of solder and brazing material. Further, the upper arm electrode 20a may be directly joined to the switching element 16a by ultrasonic waves or the like. The same applies to the lower arm electrode 20b. The connection electrode 21 is electrically connected to the coil 5, and feeds the alternating current converted by the switching elements 16 a and 16 b to the coil 5.

  The AC electrode 13 is provided so as to be joined to the transistor 17a on the end side of the upper arm electrode 20a opposite to the connection electrode 21 side and to the diode 18a on the connection electrode 21 side. The AC electrode 13 is provided so as to be joined to the transistor 17b on the end portion side of the lower arm electrode 20b opposite to the connection electrode 21 side and to the diode 18b on the connection electrode 21 side. That is, the AC electrode 13 is arranged so that the opening of the air layer 22 of the AC electrode 13 is on the transistor 17a, 17b side when assembled as the power module 6. The transistors 17a and 17b generate a larger amount of heat than the diodes 18a and 18b. Therefore, the Joule loss in the transistors 17a and 17b can be reduced by providing the air layer 22 between the upper arm electrode 20a and the lower arm electrode 20b joined to the transistors 17a and 17b having a large Joule loss. Moreover, the air layer 22 acts as a heat insulating part, and heat interference can be reduced.

  As shown in FIG. 2, the width X2 of the connecting electrode 21 orthogonal to the connecting direction in the connecting electrode 21 is such that the upper arm electrode 20a and the lower arm electrode 20a and the lower arm electrode 20a are perpendicular to the main current direction. The upper arm electrode 20a, the lower arm electrode 20b, and the connecting electrode 21 are formed so as to be equal to or larger than the width X1 of the arm electrode 20b. That is, the width X2 of the connecting electrode 21 in the longitudinal direction of the upper arm electrode 20a and the lower arm electrode 20b is equal to the width X1 of the upper arm electrode 20a and the lower arm electrode 20b orthogonal to the longitudinal direction of the upper arm electrode 20a and the lower arm electrode 20b. As described above, the upper arm electrode 20a, the lower arm electrode 20b, and the connecting electrode 21 are formed. Thereby, in AC electrode 13, it can prevent that an electric current stops flowing from the upper arm electrode 20a and the lower arm electrode 20b to the connection electrode 21. FIG.

  Although not shown in detail, the power module 6 is cooled by a cooling device through which a refrigerant flows.

  With the above configuration, when a current flows from the external power source to the power module 6, an alternating current is generated by the switching elements 16 a and 16 b, and the alternating current is supplied to the coil 5 through the AC electrode 13.

  The effect of 1st Embodiment of this invention is demonstrated.

  In the electromechanically integrated motor using the power module 30 that does not have the air layer 22 of the present embodiment, a leakage magnetic flux is generated in the stator core 8 when a current flows through the coil 5 as shown in FIG. As shown in FIG. 5, a large eddy current is generated in the AC electrode 31 due to the leakage magnetic flux. Therefore, in a motor that does not use the power module 6 of the present embodiment, heat generated by eddy current is increased.

  In addition, the main cause of aging deterioration of a material that releases heat generated in a power module or the like is temperature, and the lifetime of the material can be estimated by Arrhenius law according to the temperature environment. According to this, the higher the temperature, the shorter the life of the material. Therefore, if the cooling capacity of the motor is constant, the heat-resistant life of the material that dissipates the heat generated in the power module by the heat generated by the eddy current is reduced.

  In the present embodiment, the AC electrode 13 of the power module 6 disposed in the vicinity of the coil 5 of the motor 1 has air at a position between the upper arm P electrode 11 and the lower arm N electrode 12 when viewed from the stacking direction. Layer 22 is formed. As a result, the area of the AC electrode 13 can be reduced and the rectangular plane can be formed. When a current is passed through the coil 5, generation of eddy current in the AC electrode 13 is suppressed, and the amount of heat generated in the power module 6 is suppressed. be able to. Thereby, the heat-resistant lifetime of the power module 6 can be improved. Moreover, the lifetime of the refrigerant | coolant which cools the power module 6 can also be improved because the emitted-heat amount of the power module 6 is suppressed.

  Further, as shown in FIG. 2, the width X2 of the connecting electrode 21 is set to be equal to or larger than the width X1 of the upper arm electrode 20a and the lower arm electrode 20b, thereby preventing current from flowing through the AC electrode 13.

  In the AC electrode 13, by providing an air layer 22 between the upper arm electrode 20a and the lower arm electrode 20b joined to the transistor 17a or 17b, Joule loss generated around the transistors 17a and 17b that generate a relatively large amount of heat. In addition, the concentration of heat generation can be reduced, and the heat-resistant life of the power module 6 can be improved.

  Further, by forming the air layer 22, the air layer 22 acts as a heat insulating portion, and heat between the upper arm electrode 20 a and the lower arm electrode 20 b and between the upper arm P electrode 11 and the lower arm N electrode 12. Resistance can be increased and thermal interference can be reduced.

  Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a view of the power module 40 in the present embodiment as seen from the axial direction. FIG. 7 is a view taken in the direction of arrow A in FIG. In FIG. 7, the coil 5 and the stator core 8 are shown for explanation.

  The second embodiment will be described with a focus on differences from the first embodiment.

  In the present embodiment, the air layer 42 is formed so that the distance between the upper arm electrode 41a and the lower arm electrode 41b increases from the mounting surface back side to the mounting surface of the switching elements 16a and 16b. In other words, the wall surface 44a of the upper arm electrode 41a and the wall surface 44b of the lower arm electrode 41b forming the air layer 42 have a large distance between the wall surface 44a and the wall surface 44b from the mounting surface back side to the mounting surface of the switching elements 16a and 16b. Tapered shape. Thereby, the thermal diffusion area of the AC electrode 43 is widened.

  In the present embodiment, the wall surface 44a of the upper arm electrode 41a and the wall surface 44b of the lower arm electrode 41b are tapered, but the present invention is not limited to this, and any shape can be used as long as the heat diffusion area is widened.

  The effect of 2nd Embodiment of this invention is demonstrated.

  On the wall surface 44a of the upper arm electrode 41a and the wall surface 44b of the lower arm electrode 41b forming the air layer 42, the distance between the upper arm electrode 41a and the lower arm electrode 41b from the mounting surface back side to the mounting surface of the switching elements 16a and 16b. By forming the air layer 42 so as to increase, the heat diffusion area of the AC electrode 43 can be increased, and the heat-resistant life of the power module 40 can be improved.

  In addition, instead of the air layer 22 serving as an air layer, a member having a higher electric resistance than the upper arm electrodes 20a and 41a, the lower arm electrodes 20b and 41b, and the connecting electrode 21, such as aluminum, can be provided as the high electric resistance portion. .

  In the above embodiment, the power modules 6 and 40 are arranged so as to extend in the radial direction of the shaft 2, and the switching elements 16 a and 16 b are arranged along the radial direction, but are arranged in the axial direction of the shaft 2. Also good. In this case, the power modules 6 and 40 are arranged on the stator outer peripheral side in the case of the inner rotor type motor, and on the inner peripheral side of the stator in the case of the outer rotor type motor.

  It goes without saying that the present invention is not limited to the above-described embodiments, and includes various modifications and improvements that can be made within the scope of the technical idea.

1 Mechanical and electrical integrated rotating electrical machine (motor)
4 Stator 5 Coil 6, 40 Power module 11 Upper arm P electrode (first energizing member)
12 Lower arm N electrode (second energizing member)
13, 43 AC electrode (third energizing member)
16a, 16b switching element (first semiconductor element, second semiconductor element)
17a, 17b Transistor 18a, 18b Diode 20a, 41a Upper arm electrode 20b, 41b Lower arm electrode 21 Connection electrode 22, 42 Air layer (high electric resistance part)

Claims (5)

In the power module that is arranged in the vicinity of the coil wound around the stator and is electrically connected to the coil,
A first semiconductor element;
A first current-carrying member laminated on the first semiconductor element;
A second semiconductor element;
A second energization member laminated on the second semiconductor element;
A third energization member laminated on the opposite side of the first energization member and the second energization member across the first semiconductor element and the second semiconductor element;
The third current-carrying member has a higher electrical resistance value than the third current-carrying member at a position between the first current-carrying member and the second current-carrying member when viewed from the stacking direction. A power module comprising an electrical resistance unit. The third energizing member is
An upper arm electrode electrically connected to the first semiconductor element;
A lower arm electrode electrically connected to the second semiconductor element;
A connection electrode for connecting the upper arm electrode and the lower arm electrode;
The width of the connection electrode in the direction orthogonal to the connection direction of the connection electrode is such that the width of the upper arm electrode in the direction orthogonal to the main current direction of the current in the upper arm electrode and the lower arm electrode and the width of the lower arm electrode The power module according to claim 1, wherein the power module is not less than a width. The first semiconductor element and the second semiconductor element are configured by arranging transistors and diodes in a radial direction or an axial direction of the stator,
The power module according to claim 2, wherein the high electrical resistance portion is formed at least between the upper arm electrode and the lower arm electrode stacked on the transistor.   The high electrical resistance portion is formed so that the high electrical resistance portion spreads from the back side of the mounting surface of the first semiconductor element and the second semiconductor element toward the mounting surface. The power module according to any one of 3 to 3.   The power module according to claim 1, wherein the high electrical resistance portion is an air layer.