Power module for a power converter with optimized signal pins, power converter, electric axle drive and vehicle

Abstract

Power module (10A - D) for an inverter to supply an electric axle drive in an electric vehicle and / or a hybrid vehicle, comprising a plurality of semiconductor switching elements (12) for feeding in an input current and for generating an output current based on the fed-in input current by switching the semiconductor switching elements (12), wherein the semiconductor switching elements (12) each have a positive current electrode, a negative current electrode and a control electrode, wherein each of the electrodes is electrically conductively connected to a respective signal pin (142, 144, 146), and wherein at least one of the signal pins (142, 144, 146) extends at least sectionally vertically between the electrode electrically connected thereto and a drive device, characterized in that at least one of the signal pins (142, 144, 146) is laterally connected in a force-locking and / or form-locking manner, electrically insulated, to a conductor frame (20)wherein the lead frame (20) comprises a plurality of power lines (202) supplied with a switch current.,

Description

[0001] The invention relates to a power module for a power converter, in particular for an inverter, for supplying current to an electric axle drive of an electric vehicle or a hybrid vehicle, a corresponding power converter, in particular an inverter, a corresponding electric axle drive with such a power converter and a corresponding vehicle with such an electric axle drive.

[0002] Pure electric vehicles and hybrid vehicles are known in the state of the art, which are powered exclusively or in support by one or more electric machines as drive units.

[0003] US 2003 / 0 106 924 A1 discloses electrodes for semiconductor elements, wherein the electrodes have raised portions and are electrically connected to metallic members. A printed circuit board is also provided into which several signal pins extend from the semiconductor elements.

[0004] WO 2021 / 245915 A1 discloses a power semiconductor device comprising an electrically conductive circuit pattern, a power semiconductor element, a sealing member, and an electrically conductive post. A first post is connected to the circuit pattern, and a second post is connected to the power semiconductor element. The first post further comprises a metal pin and an electrically conductive connecting member.

[0005] DE 10 2020 211 008 A1 discloses a power converter for a vehicle that is at least partially electrically powered. The power converter has a first circuit board that has intermediate circuit capacitors, a power switch group for each AC phase, and connections for AC busbars and DC busbars. Furthermore, the power converter has a second circuit board that has a control device for controlling the power switch groups.

[0006] US 2014 / 0 246 783 A1 discloses a semiconductor device in which a printed circuit board and a semiconductor element of a semiconductor mounting plate are bonded and electrically connected via pins. The pins are press-fitting pins.

[0007] JP 2010-283107 A discloses a semiconductor module comprising a circuit board with a copper pattern applied to its surface. A semiconductor device is placed on the circuit board. A terminal is fixed to the copper pattern. A lead pin for connecting to a control substrate is connected via a hole on the copper pattern.

[0008] DE 10 2016 224 586 A1 discloses a semiconductor package comprising a substrate, a housing connected to the substrate and a plurality of press-in pins, wherein the press-in pins can be firmly connected to the housing and have at least one latching section extending from one side of the press-in pins into the housing.

[0009] To supply the electric motors of such electric vehicles or hybrid vehicles with electrical energy, electric vehicles and hybrid vehicles incorporate electrical energy storage devices, particularly rechargeable electric batteries. These batteries are designed as direct current sources, but the electric motors generally require alternating current. Therefore, a power electronics unit with a so-called inverter is typically connected between a battery and an electric motor (electric motor) of an electric vehicle or hybrid vehicle.

[0010] Such inverters typically comprise semiconductor switching elements, typically formed from transistors such as MOSFETs or IGBTs. It is known to design the semiconductor switching elements as so-called half-bridges, which have a high-side device and a low-side device. This high-side or low-side device comprises one or more parallel-connected semiconductor switching elements, which are specifically controlled during operation of the inverter in order to generate several temporally offset phase currents of an AC current from a DC current fed into the input side of the half-bridges. The phase currents are each temporally variable and generally assume a sinusoidal shape.

[0011] The semiconductor switching elements are preferably transistors such as MOSFETs or IGBTs and each have electrodes for applying a switching current to the respective semiconductor switching element (current electrodes) and for applying a switching signal (control electrode) to allow or block the switching current. Signal pins are used to transmit the switching signal. These pins are connected, on the one hand, to the control electrode and, on the other hand, to a driver device comprising a printed circuit board equipped with driver components.

[0012] In prior-art inverters, signal transmission is often delayed due to the large distances between the electrodes on the one hand and the driver device on the other, which lead to increased resistance in the signal lines. This also causes high stray inductance, which leads to voltage fluctuations or surges when the semiconductor switching elements are constantly switched on and off.

[0013] It is an object of the invention to provide a power module for a power converter, in particular an inverter, in order to at least partially eliminate the above-mentioned disadvantages.

[0014] This object is achieved according to the invention by the power module, the power converter, the electric axle drive, and the vehicle according to the independent patent claims. Advantageous embodiments and further developments of the invention are set forth in the dependent patent claims.

[0015] The invention relates to a power module for a power converter, in particular an inverter, for operating an electric axle drive in an electric vehicle and / or a hybrid vehicle. The power module comprises a plurality of semiconductor switching elements for feeding in an input current and for generating an output current based on the fed-in input current by switching the semiconductor switching elements. The power converter is preferably a DC / AC inverter. In this case, the input current is a DC current provided by a DC voltage source, and the output current is an AC current with multiple phase currents. Alternatively, the power converter can be a DC / DC rectifier (converter).In this case, the input current is a DC input current provided by a DC voltage source, and the output current is a DC output current different from the DC input current, which is preferably supplied to a vehicle battery for charging it.

[0016] The semiconductor switching elements are preferably transistors such as MOSFETs and / or IGBTs. The semiconductor material underlying the semiconductor switching elements is preferably silicon or a so-called wide-bandgap semiconductor, such as silicon carbide, gallium nitride, or gallium oxide.

[0017] The semiconductor switching elements each have a positive-pole current electrode (e.g., emitter electrode or source electrode), a negative-pole current electrode (e.g., collector electrode or drain electrode), and a control electrode (e.g., gate electrode). Additionally, each of the electrodes is electrically connected to a signal pin. The signal pins are preferably press-fit pins, each having a shaft portion for pressing into a circuit board of a driver device. After the press-fit pins are pressed in, they are received in the circuit board with a positive and / or non-positive fit, ensuring secure fixation of the signal pins and thus reliable signal transmission.

[0018] According to the invention, at least one of the signal pins extends vertically, at least in sections, from the electrode connected to it to the driver device or the circuit board, wherein at least one of the signal pins is laterally connected to a lead frame in a current-insulating, non-positive and / or positive manner, wherein the lead frame comprises a plurality of current lines supplied with a switch current. As a result, the distance between the electrode(s) on the one hand and the driver device or the circuit board on the other hand is shortened, so that the signal transmission resistance is lower. Any delays in signal transmission can be effectively reduced in this way. The control of the semiconductor switching elements is advantageously safer and more reliable. In addition, the reduced signal transmission path reduces the stray inductance in the power module.When semiconductor switching elements are continuously switched on and off, the stray inductance leads to voltage fluctuations or surges, which can impair the functionality of the semiconductor switching elements and thus also of the entire power or inverter. The reduced stray inductance therefore reduces such functional impairment. Because the coupling strength between the stray inductance and the voltage fluctuations or surges is proportional to the switching speed, the invention allows the use of WBS semiconductor materials with particularly fast switching speeds without the stray inductance causing high switching losses.

[0019] According to one embodiment, the signal pin has an S-shaped and / or wave-shaped intermediate section in a central region. The S-shaped or wave-shaped intermediate section is part of the shaft section of the signal pin, which is designed to generate a resilient effect when the signal pin is pressed or pressed against the circuit board of the driver device. This better protects the signal pin from stress or even breakage.

[0020] According to a further embodiment, the at least one signal pin has a base section that is stepped, S-shaped, disc-shaped, and / or cylindrical. The base section serves to support the signal pin against the electrode connected to it when the signal pin is inserted or pressed into the circuit board. The stepped or S-shaped base section can be formed as a one-piece or two-piece bend of the signal pin with the shaft section.

[0021] According to a further embodiment, each of the electrodes has a connection point to one of the signal pins, with the connection points being arranged in a triangular manner. This means that the connection points do not lie on a straight line, so that if adjacent connection points were connected with a straight line, an imaginary triangle would be created. This promotes a particularly stable structure of the signal pins. The connection points are preferably placed in this manner if the signal pins each have the base-side bend described above.

[0022] According to a further embodiment, the signal pins are electrically connected to each other using a plastic connector. The plastic connector ensures stable, fixed positioning of the signal pins while simultaneously providing potential and signal isolation between the signal pins. Advantageously, a connection between the signal pins, for example, to a lead frame of the power module, can be omitted, which facilitates lead frame replacement.

[0023] According to a further embodiment, the at least one signal pin is positively and / or non-positively connected to a holder at a lower end facing the electrode connected to it. This measure further increases the positional stability and locational rigidity of the signal pin(s). The holder can be designed as a signal-conducting holder with a cavity for receiving the shaft section on the underside, wherein the shaft section can be spaced from the lower edge of the cavity when received. In this case, the signal is transmitted through the combination of the holder and the shaft section. Alternatively, the holder can have a plastic stage, which is preferably supported on a substrate to which the semiconductor switching elements are connected on the underside. In this case, the signal pin(s) can extend upwards from the electrodes through the plastic stage.

[0024] According to the invention, the at least one signal pin is connected laterally to a lead frame in a current-insulating, non-positive and / or positive manner, wherein the lead frame comprises a plurality of power lines supplied with a switch current. The lead frame can additionally comprise a plurality of power connections for feeding in the DC current and for outputting the generated AC current, which are electrically connected to the power lines. The connection between the signal pin and the lead frame, which is both current-insulating and non-positive or positive, can be achieved by means of a plastic covering, in particular a plastic coating and / or plastic overmolding of the lead frame at the connection points to the signal pin(s).

[0025] According to a further embodiment, the power module is designed as a half-bridge module with a module highside and a module lowside, wherein the module highside and the module lowside each comprise one or more semiconductor switching elements connected in parallel. In this case, the half-bridge module itself can function as a complete half-bridge. Alternatively, several half-bridge modules can be combined to form a half-bridge with an expanded maximum current capacity. The module highsides are connected in parallel to form a highside of the combined half-bridge. At the same time, the module lowsides are connected in parallel to form a lowside of the combined half-bridge.In a power converter, in particular an inverter, several, for example three, such combined half-bridges can be used, each combined half-bridge forming a phase unit at whose current output one of several phase currents of the AC current is generated.

[0026] The invention further relates to a power converter for supplying current to an electric axle drive, in particular to an electric machine installed therein, having such a power module, a corresponding electric axle drive, and a vehicle having such an electric axle drive. The power converter can comprise an inverter or a rectifier. This results in the advantages already described in connection with the power module according to the invention also being applicable to the power converter according to the invention, the electric axle drive according to the invention, and the vehicle according to the invention.

[0027] The invention is explained below by way of example with reference to embodiments shown in the figures.

[0028] They show: Fig. 1-3 several schematic representations of a power module according to an embodiment in two perspective views and a side sectional view, Fig. 4-6 several schematic representations of a power module according to a further embodiment in two perspective views and a side sectional view, Fig. 7-9 several schematic representations of a power module according to a further embodiment in two perspective views and a side sectional view, Fig. 10-12 several schematic representations of a power module according to another embodiment in a perspective view, a top view and a side sectional view.

[0029] Identical objects, functional units, and comparable components are designated by the same reference symbols throughout the figures. These objects, functional units, and comparable components are identical in terms of their technical features, unless explicitly or implicitly stated otherwise in the description.

[0030] Fig. 1-3 each show a power module 10A according to an embodiment in a schematic representation. The power module 10A is designed for use with a power converter. The power converter is preferably a DC / AC inverter that converts a DC current provided by a DC voltage source (such as a battery) into an AC current with multiple phase currents. Alternatively, the power converter is a DC / DC rectifier that converts a DC input voltage into a different DC output voltage.

[0031] Fig. 1 shows the power module 10A in a schematic perspective view. The power module 10A comprises several semiconductor switching elements 12, which are arranged as in Fig. 1 is covered with a current-insulating material, preferably overmolded. In Fig. 2 schematically shows the structure of the power module 10A inside the overmolding 24. Instead of an overmolding 24, a potting can also be provided. The semiconductor switching elements 12 are mounted on a substrate 26, which has a multi-layer structure with a first metal layer 262a-b, a second metal layer 266, and an insulating layer 264 located therebetween. The semiconductor switching elements 12 are connected to the first metal layer 262a-b, wherein the connection is preferably effected by means of sintering and / or soldering and / or gluing. The first (upper) metal layer 262a-b is divided into two regions. The semiconductor switching elements 12 are arranged in the first region 262a, while in the second region only one of the power lines 202 is electrically connected to the substrate 262. A lead frame 20, which has a plurality of power lines 202, is arranged on top of the semiconductor switching elements 12.Via these power lines 202, several electrodes (not shown here) of the semiconductor switching elements 12 can be electrically contacted from the outside, for example, to feed in the DC current and deliver the AC current or phase currents to an electric motor of the electric axle drive to be powered. The lead frame 20 is, as shown in . Fig. 2, preferably connected to the semiconductor switching elements 12 and the substrate 26 by means of a sintered layer 206. As shown in Fig. As shown schematically in Figure 3, the second (lower) metal layer 266 is bonded to a top side 222 of a cooler 22 by means of a sintered layer 25, which is designed to absorb or dissipate heat generated in the power module 10A. Alternatively, an adhesive layer, a solder layer, or another connecting means can be used for this purpose.

[0032] A plurality of (here, for example, three) signal pins 142, 144, 146 are provided in the power module 10A, which extend upwards from the electrodes of the semiconductor switching elements 12 perpendicular to a top side 261 of the first metal layer 262a. The signal pins 142, 144, 146 are designed to transmit control signals in the form of electrical voltages / currents / pulses, which are provided by a driver device of the power converter (not shown here), to the electrodes of the individual semiconductor switching elements 12. A first signal pin 142 is electrically connected to the control electrode, which is designed here, for example, as a gate electrode, in order to transmit control signals (gate signals) to the control electrode. A second signal pin 144 is electrically connected to the positive-pole current electrode, which is designed here, for example, as an emitter electrode. A third signal pin 146 is electrically connected to the current electrode, which is designed here, for example, as a negative-pole current electrode.The first metal layer 262a, which functions as a collector electrode, is electrically connected. The second signal pin 144 and the third signal pin 146 are configured to detect current signals from the respective semiconductor switching element 12, for example, to adjust the gate signals based thereon for the purpose of optimizing a sinusoidal AC phase current.

[0033] The signal pins 142, 144, 146 are designed identically here, for example, and each have a head section 21, a foot section 18, and a shaft section 19 located therebetween. The signal pins 142, 144, 146 are designed, for example, as press-fit pins in this embodiment. The head section 21 has a larger diameter than the shaft section 19, which enables a secure, force-fitting connection with the driver device (or its circuit board) after the signal pins 142, 144, 146 have been inserted or pressed into the driver device (or its circuit board). The shaft section 19 has, as shown in Fig. 3, an S-shaped intermediate section 13 serves to resiliently dampen vibrations of the signal pins 142, 144, 146 during insertion or pressing into the driver device and to absorb tension. The base section 18 in this embodiment is disk-shaped and has a larger diameter than the shaft section 19 in order to enable secure support against the electrodes connected to the respective signal pins 142, 144, 146. In addition, the signal pins 142, 144, 146 are connected to the lead frame 20 by means of an overmolding 204, which further improves the positional stability and locational rigidity of the signal pins 142, 144, 146. This can potentially reduce or prevent forces acting on the semiconductor switching elements 12.

[0034] Fig. 4-6 show a power module 10B according to a further embodiment, each in a schematic representation. The structure of the power module 10B is similar to that shown in Fig. 1-3. Where features remain the same, reference is made to the embodiment already described there. Only the differences of the power module 10B compared to the embodiment explained above are highlighted below.

[0035] The signal pins 142, 144, 146 also have a head section 21 and a middle shaft section 19. In contrast to Fig. 1-3, instead of a base section, a holder 17a is provided, which is, for example, cylindrical in design with a cavity 172 into which the shaft section 19 penetrates from above and is received in a form-fitting manner. The current-insulating covering or overmolding 204 attached to the lead frame 20 is not, as in the case of the Fig. 1-3, the clamping element 16 is not directly connected to the shaft section 19, but to the cylindrical holder 17a. Preferably, the holder 17a, as shown in Fig. 5-6, two vertically opposed end walls. The upper end wall serves to define the upper boundary of the overmolding 204 of the lead frame 20, while the lower end wall is designed to support the respective signal pin 142, 144, 146 against the electrodes for improved positional stability and location. The holder 17a is a signal-conducting holder, so that the signal transmission between the driver device and the electrodes is achieved through the combination of the respective signal pin and the holder 17a.

[0036] The holder 17a can also absorb forces generated when a signal pin is inserted. After insertion, it counteracts further insertion of the signal pin via friction forces, thus also reducing the forces transmitted by a signal pin.

[0037] Fig. 7-9 show a power module 10C according to a further embodiment, each in a schematic representation. The structure of the power module 10C is similar to the Fig. 1-3 and Fig. 4-6. Where features remain the same, reference is made to the embodiments already described there. Only the differences of the power module 10C compared to the embodiments explained above are highlighted below.

[0038] The signal pins 142, 144, 146 also have a head section 21, a middle shaft section 19 and a foot section 18. In contrast to the Fig. 1-3, instead of a flat, disc-shaped base section, a higher base section 18 is provided here, which is, for example, cylindrical in shape. This measure enables a secure connection of the signal pins 142, 144, 146 at the base, so that, particularly when inserting or pressing the signal pins 142, 144, 146, which are preferably designed as press-fit pins, into the circuit board of the driver device, impairments to the signal pins 142, 144, 146, such as breakage, are effectively counteracted.

[0039] Furthermore, the signal pins 142, 144, 146 are not in a current-insulating mechanical connection with the lead frame 20, but are held by means of a holder designed as a plastic stage 17b. The plastic stage 17b here has, for example, a rectangular stage plate and several feet 175 for supporting the stage plate on the upper side 261 of the substrate 26. The feet 175 also serve to divert forces acting on the signal pins via the stage plate to the first metal layer 262a-b. This also reduces or prevents forces that could act on the semiconductor switching elements 12. The signal pins 142, 144, 146 each have a shoulder 192 that extends laterally outward from the shaft section 19. The plastic stage 17b is preferably formed by overmolding the signal pins with a plastic material. In this way, a nose 171 is in the Fig. 9 and in cross-section, which engages between the shoulder 192 and the cylindrical base portion 18. In this way, an improved holding effect of the plastic platform 17b is achieved. Furthermore, the plastic platform 17b mechanically connects the signal pins 142, 144, 146 to one another in a current- and signal-insulating manner, leading to greater positional stability and locational rigidity of the signal pins 142, 144, 146. This also allows a seal to be achieved during overmolding.

[0040] Fig. 10-12 show a power module 10D according to a further embodiment, each in a schematic representation. The structure of the power module 10D is similar to the Fig. 1-3, Fig. 4-6 and Fig. 7-9. Where features remain the same, reference is made to the embodiments already described there. Only the differences of the power module 10D compared to the embodiments explained above are highlighted below.

[0041] The signal pins 142, 144, 146 also have a head section 21, a middle shaft section 19 and a foot section 18. In contrast to the Fig.1-3, an S-shaped or stepped foot section 18 is provided here instead of a flat, disc-shaped foot section. This measure enables a stress-absorbing and vibration-damping foot-side connection of the signal pins 142, 144, 146. The insertion or pressing of the signal pins 142, 144, 146, which are preferably designed as press-fit pins, into the circuit board of the driver device can therefore be carried out more safely and with reduced risks of impairment of the signal pins 142, 144, 146. Preferably, the S-shaped or stepped foot section 18 is formed integrally with the shaft section 19 as a foot-side bend of the respective signal pin 142, 144, 146. The connection points of the foot sections 18 are arranged triangularly according to the positions of the electrodes. This triangular arrangement increases the positional stability and location stability of the signal pins 142, 144, 146 in the power module 10D.

[0042] Furthermore, the signal pins 142, 144, 146 are not mechanically connected to the lead frame 20 in a current-insulating manner, but are mechanically connected to each other in a current- and signal-insulating manner by means of a plastic connector 17c. The plastic connector 17c has three openings, preferably arranged along a straight line, for the passage of the signal pins 142, 144, 146. This measure further improves the positional stability and locational rigidity of the signal pins 142, 144, 146 in the power module 10D.

[0043] Another function of the plastic connector 17c is to provide a seal during overmolding. Since the signal pins are preferably formed as a pre-molded part with the plastic connector 17c, a good sealing effect is achieved. Reference symbol 10A-D power module 12 semiconductor switching elements 13 S-shaped / wave-shaped intermediate section 142, 144, 146 signal pins 15 Bend 17a signal-conducting bracket 17b Plastic stage 17c plastic connector 171 Nose 172 cavity 175 feet 18 Foot section 19 Shaft section 192 Shoulder 20 ladder frames 202 power line 204 Overmolding 206 sintered layer 21 Head section 22 coolers 222 top 24 Overmolding 25 sintered layer 26 Substrat 261 top 262a,b first metal layer 264 Isolation layer 266 second metal layer

Claims

[1] Power module (10A-D) for a power converter for supplying current to an electric axle drive in an electric vehicle and / or a hybrid vehicle, comprising a plurality of semiconductor switching elements (12) for feeding in an input current and for generating an output current based on the fed-in input current by switching the semiconductor switching elements (12), wherein the semiconductor switching elements (12) each have a positive-pole current electrode, a negative-pole current electrode and a control electrode, wherein each of the electrodes is electrically conductively connected to a respective signal pin (142, 144, 146), wherein at least one of the signal pins (142, 144, 146) extends vertically, at least in sections, between the electrode electrically connected thereto and a driver device, characterized bythat at least one of the signal pins (142, 144, 146) is laterally connected to a lead frame (20) in a current-insulating, non-positive and / or positive manner, wherein the lead frame (20) comprises a plurality of current lines (202) supplied with a switch current. [2] Power module (10A-D) according to claim 1, wherein at least one of the signal pins (142, 144, 146) has an S-shaped and / or wave-shaped intermediate section (13) in a central region. [3] Power module (10A-D) according to one of the preceding claims, wherein at least one of the signal pins (142, 144, 146) has a foot portion (18) which is step-shaped, S-shaped, disc-shaped and / or cylindrical. [4] Power module (10A-D) according to one of the preceding claims, wherein each of the electrodes has a connection point to a respective one of the signal pins (142, 144, 146), the connection points being arranged triangularly. [5] Power module (10A-D) according to one of the preceding claims, wherein the signal pins (142, 144, 146) are electrically insulatingly connected to one another by means of a plastic connector (17c). [6] Power module (10A-D) according to one of the preceding claims, wherein at least one of the signal pins (142, 144, 146) is connected to a holder (17a,b) in a force-fitting and / or form-fitting manner at a lower end facing the electrode connected thereto. [7] Power module (10A-D) according to claim 6, wherein the holder (17a,b) comprises a signal-conducting holder (17a) with a cavity (172) for receiving a shaft section (19) of at least one of the signal pins (142, 144, 146) on the underside, or a plastic stage (17b). [8] Power module (10A-D) according to claim 5 and one of claims 6 or 7, wherein a holder (17a) and a plastic connector (17c), each associated with at least one signal pin (142, 144, 146), seal the base of the signal pin (142, 144, 146) during an overmolding process. [9] Power module (10A-D) according to one of the preceding claims, wherein the power module (10A-D) is designed as a half-bridge module with a module high side and a module low side, wherein the module high side and the module low side each comprise one or more semiconductor switching elements (12) connected in parallel. [10] Power converter, in particular inverter, for supplying current to an electric axle drive in an electric vehicle and / or a hybrid vehicle, comprising one or more power modules according to one of the preceding claims. [11] Electric axle drive for a vehicle, in particular an electric vehicle or hybrid vehicle, comprising an electric motor, a transmission device and a power converter, in particular an inverter, according to claim 10. [12] Vehicle, in particular electric vehicle or hybrid vehicle, comprising an electric axle drive according to claim 11.

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