EP3631853A2

EP3631853A2 - Power electronic packaging

Info

Publication number: EP3631853A2
Application number: EP18724541.0A
Authority: EP
Inventors: Wei Liu; Xiaoguang Liang
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 2017-05-29
Filing date: 2018-05-14
Publication date: 2020-04-08
Also published as: WO2019011506A2; WO2019011506A3; DE102017208925A1

Abstract

L'invention concerne un encapsulage électronique de puissance comprenant : un système de refroidissement présentant une première partie, au moins une deuxième partie reliant la première partie et une troisième partie, la première et la troisième partie étant parallèle,. - une première partie de l'électronique de puissance étant connectée à au moins un côté de l'au moins une deuxième partie du système de refroidissement. - une deuxième partie de l'électronique de puissance étant montée sur l'au moins une deuxième partie du système de refroidissement de sorte que la première partie de l'électronique de puissance soit perpendiculaire à la deuxième partie de l'électronique de puissance.The invention relates to an electronic power encapsulation comprising: a cooling system having a first portion, at least a second portion connecting the first portion and a third portion, the first and third portions being parallel ,. a first part of the power electronics being connected to at least one side of the at least one second part of the cooling system. a second part of the power electronics being mounted on the at least one second part of the cooling system so that the first part of the power electronics is perpendicular to the second part of the power electronics.

Description

Power Electronic Packaging

Field of the invention

The present invention relates to a power electronic packaging according to the independent claim.

Background

US 8,432,030 B2 discloses a power electronic packaging having two substrates with multiple semiconductor chips and electronic components. A cooling of the silicon carbide (SiC) devices is disclosed as well.

Summary

The power electronic packaging according to the independent claim exhibits the following advantages over the above cited prior art: According to the invention a three- dimensional structure is used for placing the power electronics to a suitable cooling system. The cooling system exhibits a first part which is connected by an at least one second part to a third part. The first and the third part are in parallel. The first part of the power electronics is connected to at least one side of the at least one second part of the cooling system. It is possible to connect the first part of the power electronics to both sides of the second part of the cooling system. The second part of the power electronics is mounted on the at least one second part of the cooling system, so that the the largest plane of the first part of the power electronics is perpendicular to the largest plane of the second part of the power electronics, at least in view of the placement of the electric and electronic devices and/or the circuit boards which are parts of the first and the second part of the power electronics respectively. This usage of the three-dimensional structure for placing the power electronics leads to a reduction in size and therefore in weight as well. In addition a very efficient cooling of the power electronics is achieved.

The first and the third part of the cooling systems could be a cuboid each which are more or less the end fitting of the cooling system on each side. The at least one second part of the cooling system is also a cuboid but with two opposite sides which are in length and breadth much longer than the other sides of this cuboid. It is like a board. The first, the second and the third part of the cooling system could constitute a cooling system which is manufactured as a single part. That means there are not assemble together but made of one part. Alternatively, they could be fixed together by glueing, welding or any other similar technology. As explained below, the cooling system and consequently its parts could be made such that a fluid flows through them in order to transport the heat away. Alternatively, the cooling could be achieved by a Peltier system which realizes the cooling at the location where the power electronics is generating the heat. Other technologies could be employed to achieve the cooling.

The first, second and third part of the cooling system are predominately made of plastics.

The first part of the power electronics is a part of a device like an inverter. Due to the size of the power electronics which demands bigger devices than other applications in electronics the power electronics is divided in two parts. One part is connected to the second part of the cooling system and the other is mounted on this second part. This means that the first and the second part of the power electronics are perpendicular to each other. In the end this leads to the above mentioned advantages. The first part with for example devices made of silicon carbide like transistors are connected to the larger side of the second part of the cooling system. This enables to cool directly those devices which generate the vast part of the heat. The second part of the power electronics is mounted to a smaller side of the second part of the cooling system. This second part of the power electronics generates a lot less heat than the first part of the power electronics.

Power electronics are circuits which deal with power applications like an inverter or driving circuits for power applications like an electric engine or in switching high currents. Power electronics is the application of solid-state electronics to the control and conversion of electric power. All sort of suitable semiconductor materials could be used but silicon carbide and the nitrides like Gallium Nitride are preferred because those semiconductor can switch larger currents and greater heat than silicon. The planes could be real planes like circuit boards or boards to put the power electronics on. In addition, they could also be planes which are defined by a multitude of devices.

According to the dependent claims further advantages of the above described inventions are possible. The dependent claims show further embodiments of the invention.

A feature of the invention is that the first part of the power electronics is fixed by at least one clip to at least one second part of the cooling system. The fixture by using a clip is very easy in manufacturing and could also be helpful in repairing such power electronics when removing the first part of the power electronics from the cooling system. So due to lower cost and easier manufacturing this is a considerable advantage. A clip is a fixture device which uses pressure to keep something in a certain position.

Another feature of the invention is that the at least one second part of the cooling system exhibits a groove for one end of the at least one clip. This groove is manufactured in the second part of the cooling system so that the clip with one end is fixed by pressure in the groove and with the other end it is possible to keep the first part of the power electronics in its place. The clip could be manufactured of a ductile material.

Another feature of the invention is that the at least one second part of the cooling system is perpendicular to the first and the third part of the cooling system. This means especially that the two larger sides of the cuboid which is the second part of the cooling system are perpendicular to the first and third part of the cooling system. Then it is possible that those larger sides of the second part could be used for placing the first part of the power electronics on these sides.

Another feature of the invention is that three second parts of the cooling system connect the first and the second part of the cooling system, the three second parts being in parallel. This seems to be an optimum design of the cooling system since then it is possible to use those three parts which are like three arms for three phases of the alternate current which for example an inverter converts from a direct current coming from a battery. Another feature of the invention is that the at least one second part of the cooling system exhibits a heat sink. In this cuboid which is the second part of the cooling system a lamellar structure could be included which serves as a heat sink in order to distribute the heat in a larger volume. It has been known to employ a cooling system using water instead of using air in order to cool an electric power converting apparatus (inverter system) mounted on an electric vehicle. According to the present invention, by pumping a coolant such as water through the coolant passage of the heat sink, the heat sink will be actively cooled. Therefore, the power electronics (SiC)'s and switching parts attached to the heat sink will be effectively cooled. Therefore, it is possible to obtain a small-sized and compact inverter in which the generated heat on each side is effectively radiated and does not thermally interfere with each other.

Another feature of the invention is that a fluid flows through the cooling system in order to transport the heat away. A fluid for example water could be made flowing through this cooling system. This works evidently as to transport the heat away for example to another heat sink or to a compressor or anything else where the temperature of the fluid is cooled down. This constitutes a very efficient cooling system.

Another feature of the invention is that the first part of the power electronics exhibits semiconductor devices made of silicon carbide. Silicon Carbide is a semiconductor especially useful for making semiconductor devices for power electronics. For example there could be transistors made of silicon carbide which are used in inverters for converting DC current to AC current.

Another feature of the invention is that the first part and the second part of the power electronics form an inverter converting DC current to AC current. This is especially useful in electrically driven vehicles with a battery providing DC current but for an electric engine we need AC current to drive this engine. Therefore such an inverter is an essential element in an electrically driven vehicle.

Another feature of the invention is that the second part of the power electronics exhibits at least one capacitor and at least one driver board. The capacitor is used to generate ripple free DC. If the voltage increases, the capacitor will charge up. Then, while the voltage decreases, the capacitor releases its stored energy to keep the output voltage as constant as possible. The driver board is supposed to turn on / off the main power electronics such as the SiC according to a control signal.

Drawings / Figures

The figures and the following specification of those figures explains the invention in detail.

Figure 1 shows a block diagram of a basic set-up in electrically driven vehicle of battery, inverter, and electric engine,

figure 2 shows circuit diagram of an inverter,

figure 3 shows a first embodiment of the invention,

figure 4 shows a second embodiment of the invention,

figure 5 shows a third embodiment of the invention,

figure 6 shows a fourth embodiment of the invention,

figure 7 shows a three dimensional view of the fourth embodiment of the invention, figure 7a shows the fourth embodiment from second angle,

figure 7b shows the fourth embodiment from third angle,

figure 8 shows the top view of the fourth embodiment of the invention,

figure 9 shows the view from below of the fourth embodiment of the invention, figure 10 shows a side view of the fourth embodiment of the invention,

figure 11 shows a back view of the fourth embodiment of the invention,

figure 12 shows how the semiconductor devices are fixed by clips,

figure 13 shows a single clip and a group of clips,

figure 14 A, B and C shows how the semiconductor device is fixed by a clip and figure 15 shows an embodiment of the heat sink.

Description of the figures Figure 1 shows in a block diagram how an inverter 102 is contacted on one side to a battery 103 and on the other side to an electric motor 100. The inverter exhibits power electronics 103, a capacitor 104, a driver 105 and a cooling system 106.

The basic function of an inverter 102 is to convert the DC current coming from the battery 103 into an AC current for driving the electric motor 100. The main parts are a battery, an inverter, and a motor, and a control unit which is placed e.g. in a passenger compartment of the vehicle. The inverter converts the direct current from the battery into alternating current using the inverter to supply the motor with electrical power. The control unit sends driving command signals to the gate driver of the inverter to control the rotating speed and the torque of the motor.

This configuration according to Fig. 1 is used in vehicles with an electric powertrain.

Figure 2 shows a circuit diagram of such an inverter. A battery 200 is connected to the inverter 205. The gate driver 203 which is connected itself to a control board 204. This connection is between the battery 200 and the gate driver 203 is made by the DC-DC converter IC to input 202. The battery is also connected to a capacitor 201 which is connected between the two electrodes of the battery. In parallel to this capacitor 201 , six transistors 206 are connected which are used for providing three phases of the alter AC current. Therefore we have a so called three phase inverter here. This three phase inverter consists of three single phase inverter switches each connected to one of the three load terminals. For the most basic control scheme, the operation of the three switches is coordinated so that one switch operates at each 60 degree point of the fundamental output wave form. This creates a line-to-line output waveform with 6 steps. The six-step waveform has a zero-voltage step between the positive and negative sections of the square-wave such that the harmonics that are multiples of the three are eliminated. When carrier based pulse width modulation (PWM) techniques are applied to six-step waveforms, the basic overall shape or envelope of the waveform is retained, so that the third harmonic at its multiples are cancelled. If higher currents are desired, then such three phase inverters can be connected in parallel. There are other possibilities to design such a circuit. The transistors which make the three switches are connected to the three phases going to an electric motor 209. This motor drives than the load 210 which are for example the wheels of a car. A sensing signal (current signal and position signal of motor) is provided for controlling the AC output 208. The sensing circuit, e.g. a current sensor, is included in the gate driver 203. The signal from the sensor will be digitized and be sent to control board. There, it will be processed.

Figure 3 shows a first embodiment of the invention. A first part of the cooling system 300 is connected by a second part of the cooling system 301 to a third part of the cooling system 302. Those three parts could be integral parts of a cooling system, so there are manufactured together. There is an inlet 303 and an outlet 304 for passing the fluid through the cooling system. The second part 301 of the cooling system has on each side power electronics 305 and 306 connected to it. Not shown in this picture is that the second part of the power electronics is mounted on top of the second part of the cooling system 301 . Then, the first part of power electronics and the second part of the power electronics are perpendicular to each other with respect to their respective largest plane.

Figure 4 shows a second embodiment of the invention. The same reference numerals designate the same parts of the invention. In figure 4, we have instead of one second part two second parts namely 308 and 307 instead of 301 . Therefore both 308 and 307 have on both sides the first part of the power electronics connected to it. 307 exhibits the connection to the power electronics 309 and 310 whereas 31 1 and 312 are connected to 308. Again the second part of the power electronics is mounted on 307 and 308 in the above described manner.

Figure 5 shows a third embodiment of the invention. Here we have now three second parts of the cooling system which are between the first part 300 and the third part 302. We have again 301 with the first part of the power electronics 305 and 306 and now in addition another second part of the cooling system 313 with the power electronics 315 and 316 and 314 in parallel to 301 with the power electronics 317 and 318. Again above those second parts of the cooling system 301 , 313 and 314 have each mounted on a second part of the power electronics. This means that in the plane of the paper shown here the second part of the power electronics is mounted on.

It is possible that the power electronics is only on one side of the second part of the cooling system.

Figure 6 shows the cooling system of a fourth embodiment of the invention. Only the cooling system is shown. It is designated by 602. A water input 600 is flowing through the three arms of the cooling system and flowing out at the point 601 . Since the main application here for the power electronics is the inverter and we have three phases which are converted from the dc current this seems to be a suitable design of the invention for this purpose.

Figure 7 shows this embodiment from figure 6 in a three-dimensional drawing. The cooling system 706 is like in figure 6. The first part of the power electronics 703 mainly silicon carbide devices are connected to second part of the cooling system 706 using clips 702. The clips are fixed in a groove 701 . The first part of this power electronics 703 is connected to the second part of the power electronics consisting at least of the gate driver board 705 and the capacitors 704.

Fig. 7a and Fig. 7b show: A capacitor board 707 is connecting a gate driver board 705 with copper cylinders and screws 708. The gate driver board 705 is fixed to the cooling system 706 with plastic cylinders and screws 709. The SiC device 703 is soldered on the gate driver board 705.

Figure 8 shows a top view of this embodiment of the invention. The capacitors 800 and the board on which the capacitors are placed 801 are shown.

In figure 9, the view from below is shown. With the cooling system 900 and the power electronics 901 fixed to the second part of the cooling system namely the arms between the end fittings. Each arm represents a phase namely U phase, V phase and W phase. The size of this embodiment is length 330 mm and breadth 70 mm, which is very small for this application. Also the gate driver board 902 can be seen. Figure 10 shows a side view of this embodiment. The capacitors 800 are fixed on a board 801 which is connected and mounted on the second part of the cooling system 900. On the side of the second part of the cooling system a first part of the power electronics 901 is connected. This second part is 25 mm in height. Other lengths, breadths and heights are possible.

Figure 1 1 shows a back view of this embodiment. Again the capacitors 800 are shown fixed on a board 801 and the driver board 902, the cooling system 900 and the power electronics 901 .

Figure 12 shows how the clips are fixed to the groove 121 , clips are designated by 122. They fix the semiconductor devise 901 to a board 122. These clips 120 are shown in large view and in the overview. Also the cooling system 900 is shown as well as the semiconductor device 901 .

Figure 13 shows a single clip 130 and a group of clips 131 . The shown that the structure of the single clip is such that it presses between the semiconductor devices, so that they are fixed in their position.

Figure 14 shows how the semiconductor device made of silicon carbide is fixed by the clip.

In figure 14 A it is shown how the clip is put into the groove with one end. This leads to the fixture of the clip to cooling system 141 with the groove structure 140. The clip is designated by 142. The force to insert the clip is designated by 143.

In figure 14 B it is shown that the clip is fixed in the goring structure 140 by pressure 147. The clip 142 is opened so by the force 144, so that the semiconductor device 146 can be inserted by using the force 145. In figure 14 C it is shown that a still the clip 142 is fixed in the groove by 140 and 141 and on the other side the clip 142 fixes by pressure the semiconductor device 146 in its position. The pressure is designated by 147.

Figure 16 shows an embodiment of the heat sink. It is shown that the heat sink is in the second part of the cooling system 152. It has a lamellar structure 151 and also the closing 152 is shown. By the reference numeral 150 the complete structure of the three arms is shown.

Heat sinks comprise extended surfaces that are used to enhance cooling of heat dissipating surfaces. By increasing the overall surface area exposed to a cooling medium (fluid), the rate of heat transfer may be increased. Heat sinks may be fabricated using a variety of materials which employ a number of designs which act to enhance the cooling of the heat dissipating surfaces. Generally, the designs of the heat sinks are intended to decrease the impedance of the fluid flow through the heat sink. The lamellar structure 151 which is made by a thin aluminium sheet, should be connected to the closings 152 to make sure cooling of the surface of the closing 152.

Bezuqszeichen

100 electric motor

102 inverter

103 power electronics

104 capacitor

105 driver

106 cooling system

200 battery

201 capacitor

202 DC input

203 gate driver

204 control board

205 inverter

206 transistor

208 AC output

209 electric motor

210 board

300 first part of the cooling system

301 second part of the cooling system

302 third part of the cooling system

303 inlet

304 outlet

305 power electronics

306 power electronics

307 second part of the cooling system

308 second part of the cooling system

309 power electronics

310 power electronics

31 1 power electronics

312 power electronics

313 second part of the cooling system

314 power electronics 315 power electronics

316 power electronics

317 power electronics

318 power electronics

600 water input

601 point

602 cooling system

701 groove

702 clips

703 first part of the cooling system

704 capacitors

705 driver board

706 cooling system

707 capacitor board

708 copper cylinders and screws

709 plastic cylinders and screws

800 capacitors

801 board

900 cooling system

901 power electronics

902 gate driver

130 single clip

131 group of clips

140 groove structure

141 cooling system

142 clip

143 force

144 force

145 force

146 semiconductor device

147 pressure

150 heat sink structure

151 lamellar structure 152 closing

Claims

Patent Claims

1 . Power electronic packaging comprising:

- a cooling system exhibiting a first part (300), at least one second part (301 ) connecting the first part and a third part (302), the first (300) and the third (302) part being in parallel

- a first part (305) of the power electronics being connected to at least one side of the at least one second part (301 ) of the cooling system

- a second part of the power electronics being mounted on the at least one second part (301 ) of the cooling system, so that the largest plane of the first part (305) of the power electronics is perpendicular to the largest plane of the second part of the power electronics.

2. Power electronic packaging according to claim 1 , characterized in that a first part (305) of the power electronics is fixed by at least one clip (142) to the at least one second part (301 ) of the cooling system.

3. Power electronic packaging according to claim 2, characterized in that the at least one second part (301 ) of the cooling system exhibits a groove (140) for one end of the at least one clip (142).

4. Power electronic packaging according to claim 1 , 2 or 3, characterized in that the at least one second part (301 ) of the cooling system is perpendicular to the first (300) and the third part (302) of the cooling system.

5. Power electronic packaging according to claim 4, characterized in that three second parts (301 ) of the cooling system connect the first (300) and the third part (302) of the cooling system, the three second parts being in parallel.

6. Power electronic packaging according to any of the proceeding claims, characterized in that the at least one second part (301 ) of the cooling system exhibits a heat sink (150).

7. Power electronic packaging according to any of the proceeding claims, characterized in that a fluid flows to the cooling system in order to transport the heat away.

8. Power electronic packaging according to any of the proceeding claims, characterized in that the first part of the power electronics exhibits semiconductor devices made of silicon carbide.

9. Power electronic packaging according to any of the proceeding claims, characterized in that the first part and the second part of the power electronics form an inverter (102) for converting DC current to AC current.

10. Power electronic packaging according to any of the proceeding claims, characterized in that the second part of the power electronics exhibits at least one capacitor (800) and at least one driver board (801 ).