Patent Description:
The present invention relates to a cooling device for semiconductor switching elements, comprising a first main wall for carrying the semiconductor switching elements, a second main wall being opposite to the first main wall, a cooling channel that is defined by the first main wall and the second main wall and allows a coolant to flow along the main walls in a main flow direction, a first side wall and a second side wall each extending from the first main wall, wherein the main flow direction is directed from one of the side walls to the other side wall, and at least one connection channel, which leads into the cooling channel through the second main wall.

Besides, the invention relates to a power inverter device, an arrangement with a power inverter device and with an electric machine and to a method for manufacturing a cooling device.

When operating semiconductor switching elements, exemplarily within a power inverter device that supplies an electric machine of an electric driven vehicle, significant power losses are generated that may cause overtemperature failures of the semiconductor switching elements. It is known to use a cooling device for cooling the semiconductor switching elements that has a cooling channel in order to allow a coolant to flow along the semiconductor switching elements for cooling them. Cooling channels may have two parallel main walls, along which the coolant flows, and connections channels which supply or drain, respectively, the coolant. If the coolant is supplied or drained through one main wall that is opposite to the main wall carrying the semiconductor switching elements, edge regions between the other main wall and a side wall may not be cooled sufficiently.

Prior art is disclosed in documents <CIT>, <CIT> and <CIT>.

Thus, it is an object of the invention to provide an improved possibility for cooling semiconductor switching elements, particularly with respect to applications in electrically driven vehicles.

According to the invention the above object is solved by a cooling device as initially described, wherein at least one guiding device is arranged within the at least one connection channel and configured to direct the coolant towards an edge formed by the first main wall and one of the side walls.

The invention aims to avoid recirculations and/or deadwater regions around the edge by guiding the coolant towards the edge, when the coolant changes its flow direction because of a transition between the connection channel and the cooling channel. Therein, it has to be noted that due to restrictions in a manufacturing process of the cooling device, e.g. casting restrictions, an angle between the second main wall and the connection channel cannot always be formed such that the coolant reaches the edge sufficiently. Thereto, the cooling device according to the invention provides the at least one guiding device that resolves recirculations and guides the coolant into such edge regions. Advantageously, the cooling device provides an easily castable cooling channel and has an increased cooling efficiency realized by the cheap guiding device.

Preferably, a connection channel of the cooling device according to the invention is an inlet channel for supplying the coolant to the cooling channel, wherein a guiding device is arranged within the inlet channel and configured to direct the coolant towards the edge formed by the first main wall and the first side wall. This guiding device may also be regarded as first guiding device. This allows to cool edge regions near the inlet channel. The guiding device may be attached to wall of the inlet channel being opposite to the first side wall.

Therein, the guiding device may comprise a flap being bent into the direction of the edge.

Also, the guiding device may comprise a body having at least one attachment section configured to fix said guiding device in the inlet channel. Therein, an attachment section may be configured to come against the first side wall and/or an attachment section may be configured to come against a wall of the inlet channel being opposite to the first side wall and/or an attachment section may be configured to come against a wall connecting the first side wall and the or a wall of the inlet channel being opposite to the first side wall.

Alternatively or additionally, a connection channel of the cooling device according to the invention is an outlet channel for draining the coolant out of the cooling channel, wherein a guiding device may be arranged within the outlet channel and configured to direct the coolant towards the edge being formed by the first main wall and the second side wall. This allows to cool edge regions near the outlet channel. This guiding device may also be regarded as second guiding device.

Preferably, the guiding device is configured to narrow the outlet channel on a side of the outlet channel being opposite to the second side wall. Thereby, the coolant can be guided nearer towards the edge by prohibiting to flow directly into the outlet channel on the second side wall.

Preferably, the guiding device comprises a flap being bent towards the second main wall.

Alternatively, the guiding device may comprise a flap being bent towards the second side wall. Therein, the guiding device may be attached to a wall of the outlet channel being opposite to the second side wall.

The guiding device may comprises a body having at least one attachment section configured to fix said guiding device in the outlet channel. Therein, an attachment section may be configured to come against the second side wall and/or an attachment section may be configured to come against a wall of the outlet channel being opposite to the second side wall and/or an attachment section or two attachment sections, wherein the or each attachment section may be configured to come against a wall connecting the second side wall and the wall of the outlet channel being opposite to the second side wall and/or one attachment section may be configured to come against a bottom of the outlet channel.

The or each attachment section configured to come against the wall connecting the second side wall and the wall of the outlet channel being opposite to the second side wall may further be configured to come against the second side wall.

According to a specific embodiment, the body of the first guiding device and/or the second guiding device may comprise a bridge section that connects the attachment sections configured to come against the side wall and the wall opposite thereto. The body may further comprise a splitting section that extends from the bridge section along the inlet channel or the outlet channel, respectively, and splits the inlet channel or the outlet channel, respectively, into two parallel parts. Therein, the flap may extend from the splitting section.

With regard to the flap of the first guiding device and/or the flap of the second guiding device, the flap may comprise an attachment member that is bent off and configured to come against the connection channel.

The at least one guiding device may be made of a sheet material, e.g. from plastics or metal.

With respect to the cooling device according to the invention it is preferred that the cooling channel is formed by a cavity within a housing element of the cooling device. Such a cavity can be manufactured with low effort e.g. by casting. The housing element may be made of aluminum for realizing a low weight of the cooling device.

Preferably, the first main wall is formed by a base plate that closes the cavity. The second main wall may be formed by a bottom of the cavity. The at least one connection channel may be formed by through-holes extending from the cavity through the housing element.

According to the invention the above object is furthermore solved by an electrical equipment, comprising a plurality of semiconductor switching elements and a cooling device for the semiconductor switching elements according to the invention. For instance, the electrical equipment is a power inverter device.

According to the invention the above object is furthermore solved by an arrangement comprising an electrical equipment according to the invention, said electrical equipment being a power inverter device, and an electric machine being suitable to drive a vehicle, wherein the power inverter device is configured to supply the electric machine.

According to the invention the above object is furthermore solved by a method for manufacturing a cooling device for semiconductor switching elements according the invention, comprising steps of: casting the housing element so that the at least one connection channel is formed during casting; and arranging the at least one guiding element into the at least one connection channel. All statements referring to the inventive cooling device, the inventive power converter and the inventive arrangement apply analogously to the inventive method so that the above-mentioned advantages may be achieved by the method as well.

Further details and advantages of the invention are disclosed in the following, wherein reference is made to the schematic drawings, which show:.

<FIG> is a block diagram of an embodiment of an arrangement <NUM> with an embodiment of an electrical equipment <NUM> and an electric machine <NUM>. The electrical equipment <NUM> is a power inverter device that is configured to supply the electric machine <NUM>. The electric machine <NUM> is suitable for driving a vehicle such as a battery electric vehicle or a hybrid electric vehicle. Furthermore, <FIG> shows a high-voltage battery <NUM> connected to a DC link of the power inverter device or to the arrangement <NUM>, respectively.

The power inverter device comprises a DC link capacitor <NUM>, and a semiconductor switching element module <NUM> having a first semiconductor switching element arrangement <NUM>, a second semiconductor switching element arrangement <NUM> and a third semiconductor switching element arrangement <NUM>. Each semiconductor switching element arrangement <NUM>, <NUM>, <NUM> is configured to provide an output phase current of the power inverter device. Thereto, each semiconductor switching element arrangement <NUM>, <NUM>, <NUM> comprises a half-bridge formed by two semiconductor switching elements <NUM>, <NUM>. Each semiconductor switching element <NUM>, <NUM> has a transistor structure <NUM> and an antiparallel diode structure <NUM>. The transistor structure <NUM> and the diode structure <NUM> may be formed by one or multiple Power-MOSFETs or by one or multiple connections of an IGBT and a diode.

Furthermore, the power inverter device comprises a control unit <NUM> being configured to control the semiconductor switching element module <NUM> or the semiconductor switching element arrangements <NUM>, <NUM>, <NUM>, respectively, so as to provide a three-phase output voltage. The power inverter device further comprises an embodiment of a cooling device <NUM> for cooling the semiconductor switching elements <NUM>, <NUM>.

<FIG> is a longitudinal section of a first embodiment of the electrical equipment <NUM>.

The cooling device <NUM> comprises a first main wall <NUM>, which has a first side <NUM> carrying the semiconductor switching elements <NUM>, <NUM> and a second side <NUM> being opposite thereto, and a second main wall <NUM> being opposite to the first main wall <NUM>. A cooling channel <NUM> is defined by the second side <NUM> of the first main wall <NUM> and the second main wall <NUM> and allows a coolant to flow along the main walls <NUM>, <NUM> in a main flow direction <NUM>. Furthermore, the cooling device <NUM> comprises a first side wall <NUM> and a second side wall <NUM> that extend perpendicularly from the first main wall <NUM> so that the main flow direction <NUM> is directed form the first side wall <NUM> to the second side wall <NUM>.

Besides, the cooling device <NUM> comprises two connection channels, which lead into the cooling channel <NUM> through the second main wall <NUM>. The first connection channel is an inlet channel <NUM> for supplying the coolant to the cooling channel <NUM> and the second connection channel is an outlet channel <NUM> for draining the coolant out of the cooling channel <NUM>.

Within the inlet channel <NUM> a first guiding device <NUM> of the cooling device <NUM> is arranged. The first guiding device <NUM> is configured to direct the coolant towards a first edge 27a formed by the first main wall <NUM> and the first side wall <NUM>. The first guiding device <NUM> comprises a flap 26a being bent into the direction of the first edge 27a.

Besides, within the outlet channel <NUM> a second guiding device <NUM> of the cooling device <NUM> is arranged. The second guiding device <NUM> is configured to direct the coolant towards a second edge 27b formed by the first main wall <NUM> and the second side wall <NUM>. The second guiding device <NUM> comprises a flap 29a being bent towards the second main wall, therein narrowing the outlet channel <NUM> on a side of the outlet channel <NUM> being opposite to the second side wall <NUM>.

As can be seen in <FIG> the guiding devices <NUM>, <NUM> each comprise a body 26b, 29b, from which the respective flap 26a, 29a is bent off. Each body 26b, 26c partially corresponds to a shape of the inlet channel <NUM> or the outlet channel <NUM>, respectively.

The body 26b of the first guiding device <NUM> has an attachment section 26c that is attached to the first side wall <NUM> and an attachment section 26d that is attached to a wall 30a of the inlet channel <NUM> being opposite to the first side wall <NUM>. Correspondingly, the body 29b of the second guiding device <NUM> has an attachment section 29c that is attached to the second side wall <NUM> and an attachment section 29d that is attached to a wall 30b of the outlet channel <NUM> being opposite to the second side wall <NUM>.

Each body 26b, 29b further comprises a bridge section 26e, 29e that connects the attachment sections 26c, 26d or the attachment sections 29c, 29d, respectively. A splitting section 26f of the body 26b extends from the bridge section 26e along the inlet channel <NUM> and splits the inlet channel <NUM> partially into two parallel parts. Therein, the flap 26a extends from the splitting section 26f. Correspondingly, a splitting section 29f of the body 29b extends from the bridge section 29e along the outlet channel <NUM> and splits the inlet channel <NUM> partially into two parallel parts. Therein, the flap 29a extends from the splitting section 29f.

Generally, the position of the body 26b of the first guiding device <NUM> influences the fraction of fluid which is redirected into the deadwater/recirculation region of the prior art. Said position can therefore be used as a design parameter for optimizing the heat exchange.

The cooling channel <NUM> is formed by a cavity <NUM> within a housing element <NUM> of the cooling device <NUM>. The first main wall <NUM> is formed by a base plate <NUM> that closes the cavity <NUM>. The second main wall <NUM> is formed by a bottom <NUM> of the cavity <NUM>. Therein, the housing element <NUM> and the base plate <NUM> are made of aluminum, whereas the guiding devices <NUM>, <NUM> are made of a sheet material, e.g. plastics or metal.

The inlet channel <NUM> and the outlet channel <NUM> are formed by through-holes that are aligned perpendicularly to the second main wall <NUM>. Therein, the through-holes and the cavity <NUM> are formed by casting the housing element <NUM>. Within restrictions of the casting process it is also possible that the inlet channel and the outlet channel <NUM> enclose an obtuse angle with the second main wall <NUM>. After casting the housing element <NUM> the guiding devices <NUM>, <NUM> are placed into the corresponding connection channels and the cavity <NUM> is closed by the base plate <NUM>.

<FIG> is a longitudinal section of a second embodiment of the electrical equipment <NUM>. The second embodiment corresponds to the first embodiment unless differences are described in the following. Therein, identical reference signs denote identical or equivalent components.

In the second embodiment the inlet channel <NUM> is connected to a supply channel 36a. The supply channel 36a extends on an end of the inlet channel <NUM>, said end is opposite to a cooling-channel-side end of the inlet channel <NUM>, substantially in parallel to a plane defined by the first main wall <NUM>. The outlet channel <NUM> is connected to a drain channel 36b. The drain channel 36b extends on an end of the outlet channel <NUM>, said end is opposite to a cooling-channel-side end of the outlet channel <NUM>, substantially in parallel to the afore-mentioned plane.

According to the second embodiment the flap 26a of the first guiding device <NUM> extends from the wall 30a being opposite to the first side wall <NUM> towards the edge 27a. The flap 29a of the second guiding device <NUM> extends from the wall 30b being opposite to the second side wall <NUM> towards the second side wall <NUM>.

<FIG> are perspective views of the first guiding device <NUM> according to the second embodiment.

The attachment sections 26c, 26d of the body 26b have a plate-like shape. The attachment section 26c is attached to the first side wall <NUM> and the attachment section 26d is attached to the wall 30a (see <FIG>). The flap 26a is bent off the attachment section 26d. The body 26b has a further attachment section <NUM> that has the shape of a part of a wall of the inlet channel <NUM> that connects the first side wall <NUM> and the wall 30a (see <FIG>).

<FIG> are perspective views of the second guiding device <NUM> according to the second embodiment.

The attachment sections 29d of the body 29b that is attached to the wall 30b has a plate-like shape. Two further attachment sections <NUM>, <NUM> extend from the attachment section 29d. The attachment section <NUM> is attached to the second side wall <NUM> as well as to a wall of the outlet channel <NUM> that connects the second side wall <NUM> and the wall 30b. The attachment section <NUM> is attached to second side wall <NUM> and to the other wall connecting the second side wall <NUM> and the wall 30b. Another attachment section 29i is provided with the body 29b, which is attached to a bottom <NUM> of the outlet channel <NUM>. Therein, the bottom <NUM> may be considered as transition section between the outlet channel <NUM> and the drain channel 36b.

The flap 29a is provided with two attachment members 38a, 38b that are bent into the direction of the first main wall <NUM> and attached to the walls connecting the second side wall <NUM> and the wall 30b.

Optionally, with regard to the afore-mentioned embodiments pin fins <NUM> (see <FIG>), ribbon bonds <NUM> (see <FIG>) or other heat sink structures are attached the second side <NUM> first wall <NUM>. Thereby, the guiding devices <NUM>, <NUM> allow an improved heat transfer from outermost pin fins <NUM>, ribbon bonds <NUM> or heat sink structures, respectively.

Claim 1:
Cooling device (<NUM>) for semiconductor switching elements (<NUM>, <NUM>), comprising
- a first main wall (<NUM>) for carrying the semiconductor switching elements (<NUM>, <NUM>),
- a second main wall (<NUM>) being opposite to the first main wall (<NUM>),
- a cooling channel (<NUM>) that is defined by the first main wall (<NUM>) and the second main wall (<NUM>) and allows a coolant to flow along the main walls (<NUM>, <NUM>) in a main flow direction (<NUM>),
- a first side wall (<NUM>) and a second side wall (<NUM>) each extending from the first main wall (<NUM>), wherein the main flow direction (<NUM>) is directed from one of the side walls (<NUM>) to the other side wall (<NUM>), and
- at least one connection channel, which leads into the cooling channel (<NUM>) through the second main wall (<NUM>),
characterized in that
at least one guiding device (<NUM>, <NUM>) is arranged within the at least one connection channel and configured to direct the coolant towards an edge (27a, 27b), formed by the first main wall (<NUM>) and one of the side walls (<NUM>, <NUM>).