Inverter with a temperature measuring system

Abstract

An inverter is provided with a temperature measuring system which is configured to measure a temperature of semiconductor packages of the inverter, wherein the inverter has at least one phase and comprises: a base plate, at least one half-bridge arranged on the base plate with a high-side branch, each of which has at least one semiconductor package serving as a high-side switch, and a low-side branch, each of which has at least one semiconductor package arranged opposite the high-side switch, connected in parallel thereto and serving as a low-side switch, wherein each semiconductor package is provided with an electrically non-conductive sheath.The temperature measuring system comprises at least one carrier material applied flatly on or above the casing of at least one of the semiconductor packages, as well as at least one temperature measuring element arranged on or in the material, which is at least configured to detect the surface temperature of the casing of at least one semiconductor package.

Description

[0001] The present invention relates to the field of electromobility, in particular the monitoring of power semiconductors of a semiconductor package that are installed in an inverter of a power electronics module for operating an electric drive.

[0002] The use of electronic modules, such as power electronics modules, in motor vehicles has increased significantly in recent decades. This is due on the one hand to the need to improve fuel economy and vehicle performance, and on the other hand to advances in semiconductor technology. The main components of such an electronic module, also known as power electronics, are an electronic control unit (ECU), which is connected to or forms part of the vehicle's control unit(s) and receives control signals and / or information based, for example, on driving behavior or signals from other control units, and a DC / AC inverter, which is used to supply electrical machines such as electric motors or generators with multi-phase alternating current (AC).In this process, a direct current generated by a DC energy source, such as a battery or accumulator, is converted into a multi-phase alternating current. For this purpose, the inverters comprise a variety of electronic components that create bridge circuits (such as half-bridges), such as semiconductor power switches, also known as power semiconductors.

[0003] The power semiconductors are temperature-sensitive and are therefore cooled using a cooling system. Nevertheless, it is necessary to monitor the temperature of at least some of the power semiconductors so that measures can be taken in the event of overheating to prevent damage to the entire inverter system. Several options are known for monitoring the temperature of the power semiconductors. Temperature monitoring can be integrated directly into the power semiconductor module, e.g., as a temperature sensor or as sensing diodes. The temperature can also be measured directly on the semiconductor packages, i.e., on the housing (the casing) of the power semiconductors. The measurement can be performed either with contact with the housing or without contact.

[0004] The challenges of temperature measurement in inverters include the isolation between the high-voltage and low-voltage potentials, depending on the location of the temperature sensor. Other considerations include signal contacting, i.e., the distance between the measurement and further processing of the measured values, as well as the response time of the temperature sensors and the available installation space, particularly the space on the circuit board used for signal processing. Thermal contacting, including vibrations and thermal expansion, must also be taken into account when planning the temperature measurement.

[0005] Since there is still a need for improvement in the temperature measurement of power semiconductors of an inverter, the object of the invention is to provide an improved temperature measuring system for measuring the temperature of power semiconductors of an inverter.

[0006] This object is achieved by the features of the independent claims. Advantageous embodiments are the subject of the dependent claims. Further features and advantages of the invention will become apparent from the following description of exemplary embodiments of the invention, with reference to the figures of the drawing, which show details according to the invention, and from the claims. The individual features can be implemented individually or in groups in any desired combination in a variant of the invention.

[0007] An inverter is provided with a temperature measuring system which is configured to measure a temperature of semiconductor packages of the inverter, wherein the inverter has at least one phase and comprises: a base plate, at least one half-bridge arranged on the base plate with a high-side branch, each of which has at least one semiconductor package serving as a high-side switch, and a low-side branch, each of which has at least one semiconductor package arranged opposite the high-side switch, connected in parallel thereto and serving as a low-side switch, wherein each semiconductor package is provided with an electrically non-conductive sheath.The temperature measuring system comprises at least one carrier material applied flatly on or above the casing of at least one of the semiconductor packages, as well as at least one temperature measuring element arranged on or in the material, which is at least configured to detect the surface temperature of the casing of at least one semiconductor package.

[0008] In one embodiment, the temperature measuring element is formed as a temperature sensor or as a resistance strip.

[0009] In one embodiment, one temperature measuring element is arranged per semiconductor package or one temperature measuring element per phase or one temperature measuring element per high-side string and / or per low-side string or one temperature measuring element for all phases.

[0010] In one embodiment, the carrier material is routed in a U-shape over one phase or in a U-shape over all phases. In one embodiment, the carrier material is formed as two strips, each of which is routed continuously over one or all phases via the high-side strand or the low-side strand. In one embodiment, the carrier material is routed flat above the semiconductor packages.

[0011] In one embodiment, the carrier material is attached to the semiconductor package(s). In another embodiment, the carrier material is integrated into a casing of a busbar arranged directly above the semiconductor package(s).

[0012] In one version, the carrier material is designed as a foil or flexible foil or PCB or copper strip.

[0013] In one embodiment, each carrier material has at least one contact area on at least one area thereof in order to establish an operative connection between the temperature measuring system and an external processing device.

[0014] Furthermore, an electronic module is provided, comprising the described inverter.

[0015] Furthermore, an electric motor is provided, in particular an electric axle drive, for a vehicle with at least one electric drive and the described electronic module for controlling the electric motor.

[0016] Furthermore, a vehicle is provided comprising the described electric motor.

[0017] Preferred embodiments of the invention are explained in more detail below with reference to the accompanying drawings. Fig. 1 to 3 each show an inverter with a temperature measuring system according to different embodiments of the present invention. Fig. 4 to 6 each show an inverter with a temperature measuring system according to alternative, different embodiments of the present invention. Fig. 7 shows an inverter with a temperature measuring system according to another alternative embodiment of the present invention.

[0018] In the following descriptions of the figures, the same elements or functions are provided with the same reference symbols.

[0019] Currently known inverters used in the field of electromobility are often three-phase. A so-called three-phase module can be used here, in which a single base plate 2, common to all three phases P1-P3, is provided, on which semiconductor packages 4 encapsulated with a potting compound are arranged, as shown in the figures. Contact areas are routed outside the encapsulation of the semiconductor packages 4 for contact with an associated busbar. The semiconductor packages 4 are attached directly to the base plate 2, e.g., sintered onto it.

[0020] The base plate 2 serves as a carrier plate and is made of a sufficiently stable material with good thermal conductivity, such as copper, to ensure adequate heat dissipation and secure the semiconductor packages 4. It is therefore not designed as a printed circuit board and does not have any power or signal lines. It can be made of an electrically conductive material and thus also provide ground potential GND. However, it can also be made of a non-electrically conductive material, in which case the ground potential GND can also be provided by a screw.

[0021] The semiconductor packages 4 are generally arranged opposite one another, so that two of them form a half-bridge with a central AC tap 7, with one semiconductor package 4 serving as a high-side switch and the other as a low-side switch. Within each semiconductor package 4, power semiconductors, e.g., MOSFETs, IGBTs, etc., are connected in parallel.

[0022] One or more half-bridges can be provided per phase P1-P3. The figures show three half-bridges per phase P1-P3 as an example.

[0023] DC and AC power rails are arranged above the semiconductor packages 4 and are electrically contacted with the corresponding power connections of the half-bridges.

[0024] In addition, a DC busbar, preferably the DC minus busbar 6, is routed over the entire surface above the semiconductor packages 4, as shown in Fig. 7. The other busbars (DC plus and AC) are not shown, but are stacked below and above the DC minus busbar 6 and electrically connected to the associated power terminals of the semiconductor packages 4, with the AC tap 7 being provided centrally between two opposing semiconductor packages 4, as shown in the figures.

[0025] In known designs, the DC negative busbar 6 has openings so that high-voltage power and / or signal pins of the semiconductor packages 4 and / or, for example, power pins of the DC positive busbar can be routed above (to the top side) of the DC negative busbar 6 and so that the AC power connections of the AC bar located above the DC negative busbar 6 can be led to the AC taps 7 of the semiconductor packages 4 on the underside of the DC negative busbar 6. One or more openings are often also provided in the DC negative busbar 6 in order to route one or more temperature sensors to the underside of the DC negative busbar 6 in order to measure the temperature of the semiconductor packages 4.

[0026] As already mentioned at the beginning, the challenge of temperature measurement in inverters includes, among other things, the isolation between the high-voltage and low-voltage potentials, depending on the location of the temperature sensor. Other considerations include the signal contact, i.e., the distance between the measurement and further processing of the measured values, as well as the response time of the temperature sensors and the available installation space, particularly the space on the circuit board used for signal processing, located above the power rails. Thermal contact, even in the event of vibrations and thermal expansion, etc., must also be taken into account when planning the temperature measurement.

[0027] Therefore, the invention proposes a temperature measurement system for an inverter that monitors the surface temperature of the plastic casing of power semiconductors. This means that the temperature is measured directly on the casing 60 of the semiconductor packages 4. The measurement result (processed or unprocessed data) is then transmitted to a processing device via a contact area 9.3. If overheating of at least one semiconductor package 4 is detected, appropriate measures are taken, as known from the prior art.

[0028] Different embodiments of the temperature measurement system are described below with reference to the figures. All embodiments have in common that the temperature measurement elements are arranged on a layered carrier material 8. The carrier material 8 can be a film that is applied flatly to the semiconductor packages 4, or a flexible printed circuit board or a copper strip.

[0029] In a first embodiment, the temperature measuring elements of the temperature measuring system are formed as temperature sensors 9.1, which are attached to the carrier material 8, e.g., by gluing. NTC thermistors, Pt100 / Pt1000 elements, and optical sensors can be used as temperature sensors 9.1. In the latter case, the measurement data is processed in an external processing device that is operatively connected to the temperature sensor(s) 9.1 via the contact area(s) 9.3. The carrier material 8 is attached to the top side of the semiconductor packages 4, i.e., the housing, e.g., by gluing.

[0030] In Fig. 1 shows a configuration of the first embodiment, in which a separate temperature measurement system is provided for each phase P1-P3. The carrier material 8 is arranged in a U-shape, ie one leg extends over a row of the semiconductor packages 4 (in Fig. 1 upper row) and the other leg extends over the parallel row of semiconductor packages 4 (in Fig. 1 bottom row). The third leg connects the two legs across the AC tap 7 (in Fig. 1 on the right). In this version, both open ends (in Fig. 1 (left) each), a contact area 9.3 is provided, via which at least measurement data can be transmitted outside the temperature measurement system, e.g., to an external processing device. Furthermore, in this embodiment, a separate temperature sensor 9.1 is provided for each semiconductor package 4, which is arranged essentially centrally on the housing. If it is known where a temperature increase is most critical within the semiconductor package 4, the temperature sensor 9.1 can be arranged above this area, wherein the carrier material 8 can also be adapted accordingly in terms of its shape and size.

[0031] In Fig. 2 shows a configuration of the first embodiment, in which a single temperature measurement system is provided for all phases P1-P3. The difference to the embodiment in Fig. 1 is merely that the carrier material 8 is guided over all semiconductor packages 4 of all phases P1-P3, so that the two legs of the "U" become longer. Otherwise, a contact area 9.3 is provided at each of the open ends, as well as a separate temperature sensor 9.1 for each semiconductor package 4, as shown in the Fig. 1 shown version.

[0032] In Fig. 3 shows a configuration of the first embodiment, in which two temperature measurement systems are provided. Here, the carrier material 8 is formed as two parallel, separate strips that run continuously across all phases P1-P3, one of which is routed over the semiconductor packages 4 serving as the high side and the other over the semiconductor packages 4 serving as the low side. Furthermore, a contact region 9.3 is provided at each of the two open ends, as well as a separate temperature sensor 9.1 for each semiconductor package 4, as shown in the Fig. 1 shown version.

[0033] In a second embodiment, the temperature measuring elements of the temperature measuring system are formed as resistance strips 9.2, as shown in Fig. 4 to 6. These are attached to the carrier material 8, e.g., by gluing, or embedded in the carrier material 8, e.g., as conductor tracks of a PCB (printed circuit board). Temperature measurement is thus performed using a four-wire measurement, and no temperature sensors are required. The material of the resistance strips 9.2 is a thermally conductive material, advantageously copper, whose known temperature dependence is utilized for the measurement. In this case, the carrier material 8 cannot, of course, be made of copper.

[0034] In Fig. 4 shows a section with only one phase P1, which schematically illustrates two different configurations of the second embodiment. Fig. 4 upper semiconductor packages 4, a resistance strip 9.2 with its own contact area 9.3 is provided for each semiconductor package 4. In this case, the temperature of each semiconductor package 4 can be measured, whereby a mixed temperature will always be present. It can be provided that resistance strips 9.2 that lead over semiconductor packages 4 not to be measured are thermally insulated on their underside. The insulation can also be part of the carrier material 8. On the lower semiconductor packages 4 in Fig. 4 shows a resistance strip 9.2 extending across all semiconductor packages 4 with only a single contact area 9.3. In this case, the temperature of all semiconductor packages 4 over which the resistance strip 9.2 is arranged is recorded as a mixed temperature.

[0035] In Fig. 5 shows a configuration of the second embodiment, in which a single resistance strip 9.2 is guided over all semiconductor packages 4 of a phase P1. The carrier material 8 is as in Fig. 1 arranged in a U-shape, ie one leg extends over one row of semiconductor packages 4 and the other leg extends over the parallel row of semiconductor packages 4. The third leg connects the two legs via the AC tap 7.

[0036] In Fig. Figure 6 shows a configuration of the second embodiment, in which a single resistance strip 9.2 is guided over all semiconductor packages 4 of all phases P1-P3. The carrier material 8 is as in Fig. 2 Arranged in a U-shape so that the two legs of the “U” become longer.

[0037] In the Fig. 5 and Fig. 6, alternatively to a single resistance strip 9.2, several resistance strips 9.2 can be provided to monitor the temperature of each semiconductor package 4, similar to Fig. 4 above.

[0038] Since the DC negative busbar 6 is placed over the entire surface of the semiconductor packages 4, undesirable electrical interactions can occur with components placed above or below it, in particular the DC positive and AC busbars. Therefore, a complete sheath 60 of the DC negative busbar 6 is provided in areas where it covers the other busbars, i.e., where it is not electrically contacted, in order to provide electrical insulation from its surroundings, in particular the DC positive and AC busbars. The sheath 60 is therefore present in particular above the semiconductor packages 4, but not in electrical contact areas. The sheath 60 is, as already known from the prior art and therefore not described in detail, made of an electrically insulating material, preferably as a mold material, i.e., suitable for overmolding or overmolding (flow process).

[0039] As already described with reference to the DC negative busbar 6, which is placed over the entire surface of the semiconductor packages 4, the casing 60 also has various openings for passing various components from its underside facing the base plate 2 to its opposite upper side (or vice versa). The openings naturally correspond to the openings in the DC negative busbar 6, thus lying one above the other.

[0040] In one embodiment, it is provided that the temperature measuring system is integrated into the casing 60 of the DC negative busbar, in particular embedded therein, as in Fig. 7 schematically shown. This can be achieved by integrating the temperature measuring system into the casing 60 during the overmolding process. The design of the temperature measuring system can be any of the described designs, i.e. both as individual temperature sensors 9.1 applied to a carrier material 8 (see Fig. 1 to 3) as well as resistance sections 9.2 applied to a carrier material 8 (see Fig. 4-6). The contact areas 9.3 also remain. The temperature monitoring of the casing 60 of the semiconductor packages 4 can also be carried out if the temperature measuring elements 9.1, 9.2 are not in direct contact with the casing 60 of the semiconductor packages 4, but rather at a short distance from it, as is the case with the DC negative power rail 6.

[0041] The proposed temperature measuring system allows the surface temperature of the semiconductor packages 4 to be monitored, whereby a flexible arrangement of the temperature measuring elements 9.1, 9.2 is possible in a simple manner.

[0042] The proposed temperature measurement system can also be used with a multi-phase module with more than three phases or a single-phase module, in which case it is provided for each individual phase (and thus per module) of the inverter, as for example in the Fig. 1 and Fig. 5 shown version.

[0043] In all embodiments, the carrier material 8 can also be arranged over the entire surface of all semiconductor packages 4, as long as it has corresponding openings and recesses for carrying out, for example, AC contacts.

[0044] The invention has been described with reference to a DC negative power rail 6 arranged over the entire surface of the semiconductor packages 4. While this is a preferred embodiment, it is also possible for the temperature measurement system to be integrated into one of the other power rails (DC / AC), provided it is located close enough above the semiconductor packages 4.

[0045] A major advantage of the proposed temperature measurement system is that it allows for a highly modular design with regard to the number of temperature measurement elements. For example, one or more temperature measurement elements can be provided per phase P1-P3, one temperature measurement element per semiconductor package 4, or one temperature measurement element per high-side string or per low-side string of the semiconductor packages 4.

[0046] The proposed inverter 1 (DC / AC inverter) is part of an electronic module and preferably has three phases P1-P3. The electronic module is used to operate a three-phase electric motor of a vehicle and is signal-connected to an electronic control unit (ECU) that serves as the driver. The ECU is used to control and regulate the inverter and the electric motor.

[0047] The electronic module is operatively connected to the electric motor and a battery of the vehicle in such a way that the inverter converts the direct current received from the battery into alternating current usable by the electric motor, thereby driving the electric motor. The electric motor is, in particular, an electric axle drive. A vehicle, e.g., a passenger car or a commercial vehicle, advantageously has at least one such drive. List of reference symbols P1-P3 Phase 1, Phase 2, Phase 3 1 three-phase module 2 base plate 4 Semiconductor package 6 DC negative power rail 60 sheathing of 6 7 AC tap 8 Carrier material 9.1 Temperature sensor 9.2 Resistance section 9.3 Contact area

Claims

[1] Inverter (1) with a temperature measuring system which is designed to measure a temperature of semiconductor packages (4) of the inverter (1), wherein the inverter (1) has at least one phase (P1-P3) and comprises: - a base plate (2), - at least one half-bridge arranged on the base plate (2) with a high-side branch, each of which has at least one semiconductor package (4) serving as a high-side switch, and a low-side branch, each of which has at least one semiconductor package (4) arranged opposite the high-side switch, connected in parallel thereto and serving as a low-side switch, wherein each semiconductor package (4) is provided with an electrically non-conductive sheath, wherein the temperature measuring system comprises: - at least one carrier material (8) applied flatly on or above the casing of at least one of the semiconductor packages (4), and at least one temperature measuring element arranged on or in the material, which is at least designed to detect the surface temperature of the casing of at least one semiconductor package (4). [2] Inverter (1) according to claim 1, wherein the temperature measuring element is formed as a temperature sensor (9.1) or as a resistance strip (9.2). [3] Inverter (1) according to claim 1 or 2, wherein one temperature measuring element is arranged per semiconductor package (4) or per phase (P1-P3) or per high-side string and / or per low-side string or for all phases (P1-P3). [4] Inverter (1) according to one of the preceding claims, wherein the carrier material (8) - U-shaped over one phase (P1-P3) or U-shaped over all phases (P1-P3), or - is formed as two strips, each of which is continuously routed over one or all phases (P1-P3) via the high-side strand or the low-side strand, or - is guided flat above the semiconductor packages (4). [5] Inverter (1) according to one of the preceding claims, wherein the carrier material (8) - is attached to the semiconductor package(s) (4), or - is integrated in a casing of a busbar arranged directly above the semiconductor packages (4). [6] Inverter (1) according to one of the preceding claims, wherein the carrier material (8) is designed as a foil or flexible foil or PCB or copper strip. [7] Inverter (1) according to one of the preceding claims, wherein each carrier material (8) has at least one contact area (9.3) on at least one area thereof in order to establish an operative connection between the temperature measuring system and an external processing device. [8] Electronic module comprising an inverter (1) according to one of the preceding claims. [9] Electric motor, in particular electric axle drive, for a vehicle with at least one electric drive and an electronic module according to claim 8 for controlling the electric motor. [10] A vehicle comprising an electric motor according to claim 9.

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