PHASE CONNECTION FOR ELECTRIC MOTORS FOR PHASE CURRENT MEASUREMENT

Description

Technical area

[0001] The present invention relates to the technical field of electric drives that have phase connections of an electric machine. A current is applied to the phase connections to operate the electric machine and supply the phases of the electric drive with power. More specifically, the invention relates to electric drives that have a highly integrated design characterized by the integration of at least one electric motor and at least one converter as part of the electric drive. State of the art

[0002] Drive inverters comprising an AC generator are known, wherein the AC generator supplies current to a terminal panel connected to the phases of an electric motor, a power line, an AC current sensor on some phases supplying the electric motor, a current sensor on the power line, an input for receiving information including at least a value of a limit current from the source and a required torque guideline, and a controller that controls the phase currents of the electric motor based on the torque guideline, while maintaining the current in the power line at an acceptable value based on the limit current from the source. Accordingly, a maximum current can always be applied to the power source without risk of damaging it (WO 2011 / 064095 A2).

[0003] However, this requires connecting the sensor to the power line and tapping the phase current via it. This requires both current-carrying circuit elements for connection and suitable structural arrangements of the sensor relative to the power line, which complicates the implementation and arrangement of such a sensor in a drive. Furthermore, expensive measurement technology is required for measurements using such a sensor and for achieving accurate measurement results, which further increases costs even beyond the complex design. Especially in multiphase systems, as known from WO 2011 / 064095 A2, a large number of sensors or measuring devices are necessary to measure the phase currents.To achieve a compact design despite the multitude of necessary measuring devices, the use of small sensors and circuit elements is necessary, which, however, are particularly expensive given the required measurement accuracy. Furthermore, measuring via the power line, such as through connected shunt resistors, would lead to voltage drops and thus to losses in these circuit elements, which would adversely reduce the efficiency of the drive and system. Finally, the separate design of the converter as an external unit that must be connected to the motor via connecting cables is another aspect that disadvantageously increases the required installation space and the overall weight of the system.

[0004] EP 3 726 234 A1 describes a method for diagnosing an electric motor (10) having a rotor and a stator. An inverter is electrically connected to the electric motor on the output side. To measure phase currents of the electric motor, the inverter comprises current sensor devices, each assigned to a phase of the electric motor. The current sensor devices each have at least two magnetic field sensors.

[0005] CN 112 600 364 A describes a drive unit for a radial outlet connection with a motor having a motor housing, a stator, and a rotor. The drive unit further comprises a motor control device, wherein the motor control device is arranged on the radial side of the motor, wherein the motor control device comprises a housing and a circuit device, wherein the housing is fixedly connected to the motor housing, wherein the circuit device is provided in the housing, and comprises a three-phase electrode connection arrangement.In addition, the drive unit comprises a terminal assembly, wherein the electrical terminal assembly is provided at each end with an electrical control terminal end and a motor terminal end, wherein the electrical terminal end is arranged in the housing and is electrically connected to the three-phase electrode terminal assembly, and wherein the motor terminal end is electrically connected to the stator.

[0006] WO 2013 / 065849 A1 describes an inverter device comprising a busbar module electrically connected to a plurality of switching elements, a control board arranged on the side opposite the plurality of switching elements, with the busbar module sandwiched therebetween. The busbar module is further attached to an inverter housing via a module attachment portion provided in the busbar module. The control board is attached to a board attachment portion provided in the busbar module.

[0007] Furthermore, WO 2008 / 107773 A1 discloses the use of open-loop sensors with magnetic cores arranged around the current conductors to measure the current carried by the current conductor. The sensor is arranged on a circuit board, and the magnetic core is arranged in the form of a coil around an opening in the circuit board. The current conductor, whose current is being measured, runs through the opening in the circuit board and thus through the magnetic core or coil. However, this solution is also very complicated to implement, since the magnetic core or coil must be arranged in such a way that it encompasses the entire conductor carrying the current to be measured. This makes the design complicated and time-consuming, thereby increasing the construction costs. In addition, the costs of such a circuit board or printed circuit board are significantly higher than those of a circuit board or printed circuit board without openings through which the current conductor to be measured must pass.Passing the conductor through such a circuit board opening also leads to undesirable EMC influences. This means that the electronic components connected to the circuit board or printed circuit board would be severely impaired or completely disrupted in their function by the electrical or electromagnetic effects of the conductor passing through the circuit board or printed circuit board, making the application of this type of measuring principle very difficult or impossible. Furthermore, the cost of the magnetic core itself is very high, as such magnetic cores must be manufactured from expensive, highly magnetic iron with very small hysteresis to achieve meaningful measurement results. Furthermore, due to the necessary magnetic core enclosing the conductor, this variant requires significantly more space, which is not available in space-critical electric drives. The magnetic core also disadvantageously leads to increased weight.Furthermore, in this variant, the coupling of the magnetic core to the sensor on the circuit board is also required, which requires corresponding structural effort.

[0008] If, instead, no magnetic core, no coil, or no other element that absorbs or detects the magnetic field were used with a magnetic field sensor, and instead only a magnetic coreless magnetic field sensor were used, this would pose a problem with the accuracy of the measurement results. This is because the distance between the magnetic field sensor and the conductor whose current is to be measured has a very significant influence on the measurement result. A magnetic field sensor measures the magnetic field penetrating it, from which the current strength of the current carried by the conductor can be calculated. Movement or vibration changes the distance between a magnetic coreless magnetic field sensor and the conductor and thus also the magnetic flux density measured by the magnetic coreless magnetic field sensor. This is why an erroneous change in the measured current would be detected even without a change in the current to be measured.The vibrations or movements thus lead to measurement errors. This problem is inherent in the use of magnetic field sensors without a magnetic core, since in magnetic field sensors with a magnetic core, the core surrounds the entire conductor, which is why, even during vibrations or movements, the same magnetic field still penetrates the magnetic core. In other words, magnetic field sensors with a magnetic core do not simply measure a magnetic flux density, as with coreless magnetic field sensors, but rather a defined magnetic flux. Thus, the problem of measurement errors described here does not arise with magnetic field sensors with a magnetic core or those equipped with coils, since the measured magnetic flux is always defined.

[0009] In the context of the use of magnetic coreless magnetic field sensors in an electric drive, the influence of the distance between the sensor and the current conductor to be measured is extremely problematic. This is because, on the one hand, an electric drive itself causes vibrations due to the movement of the rotor, and, on the other hand, an electric drive used in vehicles is also exposed to the movements of the vehicle. Such movements and vibrations lead to the magnetic field sensor and the current conductor being subjected to constant movement and vibration, which ultimately constantly changes the distance between the magnetic field sensor and the current conductor and thus also the magnetic field penetrating the magnetic field sensor. This results in measurement inaccuracies caused by the vibrations and / or movements, which negatively affect the accuracy of the measured current value, deviating from the actual current.If electric drives are controlled based on an incorrect current value, the electric drive will ultimately be controlled and operated incorrectly, making the electric drive inefficient for practical use. In particular, the torque fidelity of an electric drive would suffer.

[0010] Another problem with using magnetic field sensors without a magnetic core is that the influence of other, external, magnetic fields cannot be separated from the magnetic field of the conductor whose current is to be measured. In magnetic field sensors with a magnetic core, such external magnetic fields are suppressed by the core. However, especially when used in electric drives, a large number of current-carrying conductors, such as those from the multiple phases of the electric drive, are located in close proximity to the current conductor of one of the phases to be measured, generating a large number of interfering magnetic fields. This also negatively influences and distorts the measured current.

[0011] Another problem with using magnetic field sensors without a magnetic core is that the flux density of the magnetic field, which the current generates in the conductor to be measured and which penetrates the magnetic field sensor, is low. This is because such a sensor is located only on one side, emanating from the conductor, whereas a magnetic core encompasses the entire conductor and amplifies the flux density by a factor of 100. Consequently, due to the elimination of the high permeability without a magnetic core, only a significantly lower flux density can occur at the sensor. This is why the sensitivity and thus the signal-to-noise ratio are disadvantageously low, which further negatively impacts the measurement accuracy.

[0012] The invention defined in claim 1 is based on the problem of minimizing the disadvantages of using magnetic-core-less magnetic field current sensors in electric drives with an integrated electric machine and integrated converter, which require precise current measurement of the phase currents for operation. Using an integrated converter, a direct current source connected to the highly integrated drive can be used, and the electric machine can be supplied with alternating current generated by the integrated converter without the need for additional parts or components. This is particularly important in the field of electromobility, since in many electric vehicles, electrical energy is stored in battery storage units, which in turn supply direct current rather than alternating current.In contrast, many types of electric motors require alternating current to operate in order to generate the desired alternating field in the electric motors, which drives the rotor in the stator of such electric motors. Since key factors in determining the efficiency of electric vehicles are their weight and power density, as well as the size and thus the required installation space of the drive components of the electric vehicles, a key objective of the present invention is to also reduce the size of the drive components of electric vehicles and thereby save weight while still maintaining the highest possible system performance. Ultimately, high efficiency can only be ensured with precise control of the drive, which is why one focus of the present invention is also on improving the accuracy of the phase current measurement results.

[0013] These problems are solved by the features listed in patent claim 1. Thus, the highly integrated electric drive comprises an inverter and an electric motor. At least one phase connection of a slot bar of the electric motor is located outside the slot of the corresponding phase. A magnetic field measurement principle is used to measure the current, with a coreless magnetic field sensor positioned at a bend in the phase connection.

[0014] The advantages achieved by the invention are that, instead of magnetic-core magnetic field sensors, magnetic field sensors without a magnetic core or coil can be used to measure phase currents without losing the measuring accuracy of magnetic-core magnetic field sensors. Furthermore, the use of magnetic-coreless magnetic field sensors simplifies the design, since such sensors, unlike shunt resistors or magnetic-core magnetic field sensors, do not have any circuit elements that need to be coupled to the current conductor to be measured or that need to be arranged around the current conductor to be measured. This increases system efficiency, and the simple design significantly reduces space requirements and manufacturing costs compared to conventional solutions.Despite the use of coreless magnetic field sensors, high measurement accuracy is achieved because the sensor performs the measurement at a bend in the conductor whose current is to be measured. This bend focuses the magnetic field at the sensor, which is why the magnetic field penetrating the coreless magnetic field sensor is significantly stronger, which advantageously increases measurement accuracy and the signal-to-noise ratio.The use of a solid slotted bar, which is connected to the converter in the form of an equally solid phase connection, instead of a wire winding with exposed winding ends, results in improved rigidity and robustness against accelerations acting on the slotted bar and especially the phase connection, so that vibrations or movements have only a minimal impact on the distance between the magnetic field sensor and the current conductor to be measured, i.e., the phase connection. This reduces negative interference on the measurement result of the coreless magnetic field sensor.

[0015] Advantageous embodiments of the invention are specified in the subclaims.

[0016] In one embodiment, an electric drive comprises an inverter, an electric machine which comprises a plurality of phase current branches, wherein the electric machine and the inverter are arranged together in a housing, and at least one magnetic core-less magnetic field sensor for measuring a current of at least one of the plurality of phase current branches, wherein at least one phase current branch of the plurality of phase current branches comprises a slot bar which is arranged at least partially in a slot of the electric machine and which forms a phase connection outside the slot, and wherein the phase connection has a curvature in the region of which the at least one magnetic core-less magnetic field sensor is arranged.

[0017] In one embodiment, the phase connection can extend at least partially in a plane in which a normal to the rotation axis runs. In other words, in a plane normal to the rotation axis. The rotation axis is a rotation axis of a rotor of the electric drive.

[0018] In one embodiment, the phase terminal may be curved away from the direction of the normal within the plane normal to the axis of rotation.

[0019] In one embodiment, the at least one magnetic coreless magnetic field sensor can be arranged on a circuit board.

[0020] In one embodiment, the at least one coreless magnetic field sensor can have only one physical connection that connects the at least one coreless magnetic field sensor to the circuit board. The one physical connection can comprise one or more physical contacts that connect the at least one coreless magnetic field sensor exclusively to the circuit board and not to other components or parts, such as a magnetic core.

[0021] In one embodiment, the at least one magnetic core-less magnetic field sensor may consist of a surface-mounted component that is arranged as an integrated circuit in a separate housing on the circuit board.

[0022] In one embodiment, the at least one magnetic core-less magnetic field sensor may consist of a wired component that is arranged as an integrated circuit in a separate housing on the circuit board.

[0023] In one embodiment, the phase connection may run at least partially parallel to a plane on which the circuit board is arranged.

[0024] In one embodiment, the circuit board can be a circuit board for controlling the converter. In another embodiment, the circuit board can be a current measurement circuit board that has a signal-transmitting connection to a circuit board for controlling the converter. In this embodiment, the sensor is not located on the circuit board for controlling the converter, and the sensor can be arranged with the current measurement circuit board at any location on the electric drive.

[0025] In one embodiment, the at least one magnetic coreless magnetic field sensor may be a Hall sensor and / or one of a closed-loop sensor or an open-loop sensor and / or one of a magnetoresistive sensor, an anisotropic magnetoresistive effect (AMR) sensor, a giant magnetoresistive (GMR) sensor, a tunneling magnetoresistive (TMR) sensor, or a colossal magnetic resistance (CMR) sensor.

[0026] In one embodiment, the phase connection can have a flexible section with a curve that connects the phase connection to the part of the slot bar that is at least partially arranged in the slot of the electric machine. The flexible section can be mechanically flexible at least in one direction of a rotational axis of a rotor of the electric machine in order to compensate for mechanical stresses that occur at least in the direction of the rotational axis.

[0027] In one embodiment, the at least one magnetic core-less magnetic field sensor for measuring the current of at least one of the plurality of phase current branches can be arranged at the flexible section and in the region of the curvature of the flexible section.

[0028] In one embodiment, the flexible portion may extend orthogonally to the direction of the rotation axis, wherein the curvature of the flexible portion has a U-shape.

[0029] In one embodiment, an O-ring can enclose the phase connection and divide a space located around the phase connection into two subspaces and separate them from each other in a fluid-tight manner.

[0030] In one embodiment, at least one of the sub-chambers may be filled with a potting compound.

[0031] In one embodiment, the encapsulation can be thermally conductive and electrically insulating, and the encapsulation can be thermally coupled to a bearing plate of the electric drive. Instead of or in addition to the bearing plate, the encapsulation can be thermally coupled to a heat sink of the electric drive.

[0032] In one embodiment, the electric drive may additionally comprise an acceleration sensor.

[0033] In one embodiment, the converter may have an architecture with at least three planes that are orthogonal to the rotation axis and that are offset from one another in the direction of the rotation axis.

[0034] In one embodiment, the converter may comprise a first level, wherein a circuit board for controlling the converter is arranged on the first level.

[0035] In one embodiment, the at least one magnetic coreless magnetic field sensor can be arranged on the circuit board for controlling the converter in the first level.

[0036] In one embodiment, the converter may have a second level, wherein at least one semiconductor component of the converter is arranged on the second level.

[0037] In one embodiment, the portion of the phase connection which extends at least partially in a plane in which the normal of the rotation axis runs may be arranged on the second plane.

[0038] In one embodiment, the converter may have a third level, wherein at least one heat sink for cooling the semiconductor components is arranged on the third level.

[0039] In one embodiment, the third level may have a DC connection with a negative pole, wherein the second level may have a DC connection with a positive pole.

[0040] In one embodiment, the converter may have a fourth plane, wherein the fourth plane has a DC voltage connection consisting of a positive pole and a negative pole, wherein the portion of the phase connection which extends at least partially in a plane in which the normal of the rotation axis runs is arranged on the fourth plane.

[0041] In one embodiment, the converter may have a fourth plane, wherein the portion of the phase connection which extends at least partially in a plane in which the normal of the rotation axis runs is arranged on the fourth plane, and wherein the third plane has a DC voltage connection with a negative pole and wherein the second plane has a DC voltage connection with a positive pole.

[0042] The foregoing summary serves to summarize some embodiments to provide a basic understanding of the aspects of the subject matter described herein. Accordingly, the features described above should not be construed to limit the scope of the subject matter described herein. Furthermore, the above and / or subsequent embodiments may be combined in any suitable combination to provide further embodiments. Additional features, aspects, and advantages of the subject matter described herein will become apparent from the following detailed description, drawings, and claims. Drawings

[0043] To describe how the above-described embodiments of the invention are implemented, as well as to define other advantages and features of the disclosure, a more detailed description is provided below. Aspects of the description are illustrated in the accompanying drawings, wherein like numerals indicate like elements. With the understanding that these drawings illustrate exemplary embodiments of the invention and are therefore not to be considered limiting in scope, the embodiments will be further explained in additional detail below through the use of the accompanying drawings. Fig. 1 shows an electric drive in a perspective view. Fig. 2 shows a part of a stator of an electric drive with a phase connection in a perspective view. Fig. 3shows a part of a stator of an electric drive with a phase connection in a perspective view. Fig. 4 shows a part of an inverter of an electric drive with a phase connection in a perspective view. Fig. 5 shows a part of an inverter of an electric drive with a phase connection in a perspective view. Detailed description

[0044] The invention is explained below with reference to the drawings, illustrating the structure and mode of operation of the invention shown. The present disclosure will be better understood in light of the following explanations: An open-loop sensor is generally understood to be a magnetic field sensor, also known as a Hall-effect sensor, with a magnetic transducer to generate a voltage proportional to the measured current. This signal is then amplified to produce an analog output signal proportional to the current flowing in the conductor. The conductor is passed through the center of a ferromagnetic core, also known as a magnetic core, to concentrate the field, and the magnetic transducer is placed in the gap of the core.

[0045] In contrast, a closed-loop sensor is a magnetic field sensor that includes a coil actively driven by the current sensing circuit to generate a magnetic field that opposes the field generated by the current in the conductor. In an open-loop configuration, any nonlinearity or drift in the sensitivity of the magnetic field current sensor IC over temperature can lead to errors, which can be prevented by using the actively driven coil. Closed-loop current sensors therefore require not only ferromagnetic cores but also a coil and additional higher-power amplifiers to drive the coil. Due to their increased complexity, closed-loop sensors are also larger and consume more power, as they must drive the compensation coil, and are more expensive due to the additional coil and drive circuit.The efficiency of the system is therefore also disadvantageously reduced by such sensors.

[0046] A coreless magnetic field sensor is a sensor that does not have a magnetic core or a coil through which a current conductor, whose current is to be determined with the coreless magnetic field sensor, passes. A coreless magnetic field sensor can therefore be placed on, near, i.e., in the vicinity of, or next to a current conductor, whose current is to be determined with the coreless magnetic field sensor. The freedom to position the magnetic field sensor on, near, or next to the current conductor is limited by the fact that the coreless magnetic field sensor must be placed within the effective range of the magnetic field that forms around the current-carrying current conductor.In some coreless magnetic field sensors, the magnetic flux must also occur perpendicular to the measuring surface. In other, so-called 2D or 3D sensors, however, the vector of the magnetic flux can be measured, and in these, an arrangement oriented perpendicular to the magnetic flux is not necessary. The present invention is not limited in this regard, and the exemplary embodiments included in the following description encompass both variants, since both a perpendicular and a deviating arrangement and both types of coreless magnetic field sensors can be included. If these requirements are met, the coreless magnetic field sensor can be used for the present invention. A coreless magnetic field sensor can also be understood as a Hall effect-based sensor.The functioning of magnetic field sensors and their subtypes is known to the person skilled in the art, which is why a description of the exact structure of the sensors themselves is not given here and why all types of magnetic field sensors can be used for the present invention.

[0047] An electric vehicle is any vehicle that has an electric drive and uses this at least partially, as in hybrid vehicles, or solely, as in vehicles with only one or more electric drives, to propel the vehicle. Boats or ships, motor vehicles such as cars, buses or trucks, as well as aircraft such as airplanes, drones or helicopters, rail vehicles or other vehicles that fall into these categories, as well as small vehicles such as electric scooters and electric bicycles, can all be considered electric vehicles. This list is not intended to be an exhaustive description, but merely provides examples of types of vehicles that, if they have an electric drive, are to be considered electric vehicles.

[0048] In this context, an electrical machine is understood to be an electrical machine that is primarily used as a drive in motor operation, but can also be used in generator operation, for example for energy recovery. An electrical machine can alternatively be referred to as a motor and comprises a rotor and a stator with slots, whereby the slots of the stator are not filled with windings, which usually consist of several turns of a wire winding, such as a copper wire winding, but with bars. These bars are solid metal elements that, unlike conventional wire windings, almost completely fill the slots. Almost completely filled means that the fill level in the slot is, for example, over 80%, or between 80 and 90%, or over 90%. In technical terms, a slot bar corresponds to a winding with a number of turns equal to 1 / 2.However, a slotted bar is more robust and stable than a wire winding and a slotted bar is manufactured as a solid metal component, for example by an extrusion process or another suitable process such as casting. The bar can be made of aluminum or any other conductive metal such as copper, or even of another electrically conductive material such as graphite. In order for such a slotted bar or a part of the slotted bar leading out of the slot, which represents a phase connection, to have a curvature, it is necessary to produce the phase connection of the slotted bar in a targeted manner, for example using an appropriately curved casting mold or by means of a specially suitable bending machine. A curvature therefore means sectional deformation or bending.This refers to a design of the phase connection that deviates from the uniform, for example, rod-shaped or cylindrical shape of the phase connection and that cannot be created solely by conventional winding or other arrangement, or simply by conventional bending of a wire of a winding after the phase connection has been manufactured, because the solid and robust phase connection can no longer be easily bent into any desired shape or arranged in a correspondingly curved manner after its manufacture. Furthermore, the curvature can also be implemented in the form of a tapered phase connection.

[0049] A printed circuit board (PCB), also known as a printed circuit board (PCB), is a carrier for electronic components that serves to mechanically attach and electrically connect these components. Printed circuit boards consist of an electrically insulating material on which electrically conductive connections, also known as traces, are applied. A printed circuit board (PCB) can also be designed with multiple layers.

[0050] Fig. 1shows an electric drive 10 in a perspective view. The electric drive 10 comprises a converter 11, which is arranged as an integrated part in the electric drive 10. It is therefore an integrated converter that is arranged in the housing of the electric drive 10. The integrated arrangement of the converter enables the electric drive 10 to be designed to be particularly compact. This is because converters are usually used as separate or external devices, so that an additional housing, circuit elements and electrical coupling elements would be required, all of which in turn take up space. This leads to a larger space requirement for the drive system as well as a higher system weight. Both are disadvantageous, especially when used for electric vehicles of any kind.

[0051] The electric drive 10 also includes an electric machine 12, which is an electric machine integrated into the electric drive 10. Although one electric machine is used to simplify the description, the electric drive 10 according to the present invention can also include multiple electric machines and is not limited to one electric machine. An electric machine 12 includes at least one rotor and a stator. Slots are provided in the stator through which phase current branches run. The phase current branches serve to generate a magnetic field that constantly changes due to the alternating current present in the phase current branches. In the case of an asynchronous machine, the change in the field in the rotor of the electric machine induces voltages that generate currents, which cause the rotor to rotate and thus the electric machine to move.In the case of a synchronous machine, the change in the field between the rotor and stator generates magnetic energy, which the system attempts to minimize by rotating the rotor. However, the operation of an electrical machine 12 is known to those skilled in the art and will therefore not be described in further detail here. The electrical machine 12 is neither limited to an asynchronous machine nor a synchronous machine, but can be one of these.

[0052] The electric drive 10 also includes a connection box 13, which is arranged on the motor casing 16 of a housing 15 of the electric drive 10. The motor casing 16 represents the housing wall of the housing 15 in the area of ​​the electric machine 12, and the motor casing 16 could also be referred to as the machine casing. The connection box 13 serves to connect the electric drive 10 to one or more external energy sources that are not shown in the drawings. For this purpose, cables 14 leading from one or more direct current sources, such as a battery or a battery system of an electric vehicle, are coupled to the connection box 13 and the electrical connections provided therein. In this way, the electric drive 10 can be supplied with direct current, which is then converted into alternating current by the converter 11 to ultimately supply the phase current branches of the electric machine 12 with alternating current.For the supply of power, the electric drive 10 has further electrically conductive conductors within the housing 15, which are not shown in the drawings and which ensure the electrically conductive connection between the components of the electric drive 10.

[0053] Fig. 2 shows a part of a stator 20 of an electric machine 12 of an electric drive 10 with a phase connection 22 of a phase current branch in a perspective view. The stator 20 with the Fig. 2 The components shown can be mounted in the housing 15, as shown in Fig. 1 shown. However, it can also be arranged in any other housing of an electric drive. The stator 20 is made of metal and can be manufactured in the form of a sheet metal laminate, but is not limited to this. The stator comprises a slot 23 in which the slot bar 21 is arranged. As shown in Fig. 2However, as shown, the stator has a plurality of slot bars and slots. The slot bar 23 forms part of a phase current branch, which is connected to power-supplying components of a converter 11 through the phase connection 22. The phase connection is a part of the slot bar 21, which is led out of the slot and extends through various other elements of the electric drive 10, which are Fig. 2 are not shown. Thus, the phase connection 22 enables electrical coupling of the slot bar 21 to the converter 11.

[0054] The slot bar 21 is designed as a solid metal component. This provides it with high rigidity and robustness. The phase connection 22 is also designed as a solid metal component, with a cross-sectional area essentially corresponding to the cross-section of the slot bar 21 and thus exhibiting at least the same level of rigidity and robustness as the slot bar 21. Such a solid design not only increases the longevity of these components but also ensures that the phase connection 22 is at least as resistant to the effects of acceleration due to vibrations or movements caused by the operation of the electric drive 10 as the slot bar 21.This allows the distance between the phase terminal 22 and a magnetic field sensor used to measure the phase current carried by the phase terminal 22 to remain constant or to change only slightly, thereby increasing measurement accuracy and reducing measurement errors due to a change in the distance between the phase terminal 22 and a magnetic field sensor. Although the phase terminal 22 is in . Fig. 2 While the phase connection 22 is shown offset from the rotational axis of the rotor of the electric machine 12, the phase connection 22 can also be arranged as a direct extension of the slot bar 21, i.e., not offset from the slot bar 21, or offset from the slot bar 21 in a different direction. The lateral offset or distance can also be freely selected to meet the design requirements of the electric drive 10.

[0055] The phase connection 22 has a Fig. 2In the embodiment shown, the phase connection 22 also has a section that is offset laterally or laterally from the axis of rotation of the rotor of the electric drive 10. This section of the phase connection 22 runs within a plane in which a normal to the axis of rotation runs. Thus, the phase connection 22 runs and extends at least partially, specifically in the form of the laterally or laterally offset section, in a plane in which a normal to a rotational axis of the rotor of the electric drive 10 also runs. However, the phase connection can also be arranged and designed differently from this. In addition, the phase connection 22 can also be curved away from the direction of the normal within this plane, for example, curved radially outwards like a paddle wheel.It is only essential that the phase connection 22 ensures the electrical coupling of the slot bar 21 with the converter 11 and that it has the previously described necessary robustness and rigidity in order to minimize the influence of vibrations or movements on the position of the phase connection 22.

[0056] In addition, the phase connection 22 must have a bend 24. Curving the phase connection 22 focuses the magnetic field generated by the phase current conducted by the phase connection. This allows a significantly stronger magnetic field to be applied to the magnetic field sensor, even with a coreless magnetic field sensor located in the area of ​​the bend 24. This measuring principle is based on the current being forced onto a partially circular path by the bend 24. According to the Biot-Savart law for a conductor loop, this leads to an amplification of the magnetic field by a factor of π, i.e., by more than three times.In addition to pure signal amplification, this also leads to an improvement in the signal-to-noise ratio, since the curvature 24 only amplifies the signal to be measured compared to the magnetic core-less sensor located in the area of ​​the curvature 24, and not the interference signals from other magnetic fields, such as those from neighboring phase connections. The curvature 24 thus significantly increases measurement accuracy without the need for a magnetic core, resulting in cost, space, and weight savings.

[0057] In one embodiment of the invention, the electric drive 10 in the electric machine 12 comprises twelve phase current branches with which the slot bars of the stator 20 are supplied. Thus, not every individual slot bar necessarily has its own phase connection, such as the phase connection 22 of the slot bar 21 in Fig. 2Instead, several bars can be coupled to each other and to the stator, allowing one phase connection to supply power to several slot bars of the stator. Thus, the number of slot bars could be increased, as in Fig. 2 shown, 48 and these 48 slot bars can be connected by twelve phase connections, of which only one is in Fig. 2 shown, are supplied with current, so that four slot bars of the stator are interconnected per phase connection. These interconnected slot bars and the associated phase connection then form a phase current branch within the meaning of the present application. However, the number of slot bars and phase current branches or phase connections may deviate from the number specified here without adversely affecting the present invention, in order to adapt the electric drive to its respective intended use and to be able to optimize it accordingly.

[0058] In Fig. 2The section of the phase connection 22, which is offset laterally from the rotational axis of the rotor of the electric drive 10 and which extends within a plane in which a normal to the rotational axis runs, is shown as arranged on an assembly 25 consisting of several semiconductor switches. The semiconductor switches are in turn connected via electrically conductive connections located in Fig. 2on the right side of the assembly 25 are shown as curved upwards, are coupled to the power supply of the electric drive 10. The connections arranged on the left side of the assembly 25 and shown as curved upwards are used to connect the semiconductor switches to the electronic components of the converter 11, which control the converter 11. The semiconductor switches of the assembly 25 convert the direct current fed in by the power supply to the alternating current with which the phase connection 22 is supplied. In this case, the power supply, as previously with regard to Fig. 1 described, by the cables 14 and the connection box 13 of the electric drive 10. In one embodiment of the present invention, the phase connection 22 is supplied with alternating current by semiconductor switches of the converter 11. In particular, the converter 11 can be connected to a circuit board which is Fig. 2not shown and which carries the electronic components required to control the converter 11. The laterally offset design of the phase connection, including the thus laterally offset curvature 24 of the phase connection 22, is advantageous in a converter architecture designed in this way, because this section of the phase connection 22 thus runs at least partially parallel to a plane of further electronic components of the converter 11, such as the circuit board 51, which with regard to Fig. 5will be explained further. In particular, the magnetic field sensor without a magnetic core for measuring the phase current can also be mounted on the circuit board of the converter 11. Such an arrangement can automatically result in an arrangement of the sensor through which the magnetic flux occurs essentially perpendicular to a measuring surface of the sensor. However, it is also possible to deviate from this embodiment if the converter architecture deviates from the arrangement of the circuit board 51 of the converter 11 described here, which is possible depending on the requirements regarding the size and performance of the electric drive 10. Furthermore, it is also possible to deviate from this arrangement if the curvature is arranged at a different point on the phase connection 22. Thus, the at least one magnetic field sensor without a magnetic core 50 can also be arranged on a circuit board for measuring current (not shown in Figs.shown), which has a signal-transmitting connection to a circuit board for controlling the converter 11. In this embodiment, the sensor 50 is not arranged on the circuit board 51 for controlling the converter 11, and the sensor 50 can be arranged with the circuit board for current measurement at any location on the electric drive, for example on a flexible section 32. Such a different variant is described below with regard to . Fig. 3 further explained.

[0059] Fig. 3 shows a part of a stator 20 of an electric drive 10 with a phase connection 22 in a perspective view. Unlike in the embodiment shown in Fig. 2 and which is described above, the phase connection 22 has, according to an embodiment shown in Fig. 3is shown, however, has a flexible section 32, which is itself curved and thus represents a curvature and which connects the phase connection 22 to a slot bar 21, which is arranged at least partially in a slot of the stator 20 of the electrical machine 12. The other elements which are shown in Fig. 3 are shown are to those in Fig. 2 identical, which is why these elements will not be described again below. Accordingly, the flexible section 32 of the phase connection 22 is optional to the embodiment as with regard to Fig. 2 described or from the embodiment according to Fig. 3removable. The flexible section 32 serves to provide additional mechanical decoupling of the phase connection 22 in order to minimize the effects of vibrations or movements on the position of the phase connection 22. During operation of the electrical machine 12, movements caused by operation, particularly in the direction of the rotor's rotation axis, can lead to greater mechanical stresses. Therefore, the flexible section 32 can be mechanically flexible at least in the direction along which the rotor's rotation axis of the electrical machine 12 runs, in order to be able to compensate for mechanical stresses that occur at least in the direction of the rotation axis. This can ensure that the distance between the phase connection 22 and a magnetic core-less magnetic field sensor provided for measuring the phase current does not change or changes only very slightly, whereby measurement errors can be avoided, as already described above.

[0060] The flexible section 32 of the phase connection 22 is as in Fig. 3As shown, it is designed to form an extension of the slot bar 21 outside the slot, which has a U-shape. In other words, the flexible section is curved, with the curved shape forming an overall angle of approximately 180°, although the angle can vary and is not fixed. Due to this shape, the flexible section has a higher, spring-like deformability, which contributes to the previously described minimization of positional changes of the phase connection 22 caused by vibrations or movements. The flexible section 32 can, but does not have to, be designed as a standalone component and can be an integral part of the phase connection 22. Furthermore, the curved shape of the flexible section 32 has the same effect as the curvature 24 of the phase section 22.Due to the curved path of the conductor section of the phase connection 22, which corresponds to the flexible section 32, the current is forced onto a partially circular path. According to the Biot-Savart law for a conductor loop, this leads to an amplification of the magnetic field by a factor of π, i.e., by more than three times. This further emphasizes that the bend 24 is not a tapered section, as shown in . Fig. 2 and Fig. 3 depicted, but merely needs to represent a shape of the phase connection 22 that modifies the conductor such that the current is at least partially forced onto a circular path. The flexible section 32 of the phase connection 22, like the bend 24, can thus serve as a suitable location for measuring the phase current, where a magnetic field sensor without a magnetic core can determine the current with minimal measurement errors.

[0061] Accordingly, the magnetic core-less magnetic field sensor in all embodiments of the present invention can also be mounted on or in the region of the flexible section 32, which itself represents a curve. It would then not be necessary to mount another sensor on the curve 24, and the design of the phase connection with the curve 24 can then be omitted. However, the curve 24, as shown in Fig. 3shown, can continue to be part of the phase connection 22 despite the flexible section 32, so that it is also possible to attach a magnetic core-less magnetic field sensor on or near the flexible section 32 and the bend 24, which leads to increased redundancy and reliability. As already described above, the at least one magnetic core-less magnetic field sensor 50 can in this case be arranged on a separate, i.e., an additional current measuring board that is different from the board 51 for controlling the converter 11. Such a separate current measuring board can have a signal-transmitting connection via which data generated by the sensor can be transmitted to the board 51 for controlling the converter 11. This connection can be a wireless connection or a wired connection, i.e., a connection with one or more electrical conductors.This embodiment allows for greater flexibility in the design of the electric drive 10, allowing the structure to be optimized according to the space-saving requirements in various parts of the electric drive 10. This results in a significant space-saving component, particularly in systems with a high number of phase current branches, since not just one sensor, but a number of sensors corresponding to the number of phase current branches can then be arranged at any other location of the at least one phase connection 22 with a curve where more space is available for the sensors.

[0062] Thus, the present invention requires that the phase connection has a curvature arranged at any point of the phase connection, for example in the form of a taper or in the form of a bend, whereby the amplification of the magnetic flux is achieved as previously explained. Whether this curvature is arranged at a laterally offset portion of the phase connection 22 as in Fig. 2 shown, or on a bent flexible section 33 of the phase terminal 32 as in Fig. 3 shown, or further deviating from this, is arranged at another location of a possibly differently designed phase connection, is not relevant as long as the requirements with regard to robustness and thus with regard to insusceptibility to vibration and movement, space saving and focusing of the magnetic field of the phase connection are met in accordance with the previous description.

[0063] Fig. 4 shows a part of a converter 11 of an electric drive 10 with a phase connection 22 in a perspective view. In Fig. 4 are further parts of the electric drive 10, which are Fig. 2 or Fig. 3not shown. The phase connection 22 is guided through various levels of the converter. For this purpose, openings can be provided in these levels through which the phase connection 22 runs. Accordingly, the phase connection can run through a space of such openings. For additional mechanical stabilization and to further minimize the effects of vibrations or movements on the position of the phase connection 22, an O-ring can enclose the phase connection 22 so that a space around the phase connection and through which the phase connection 22 extends is divided into two sub-spaces because the O-ring rests against the walls of the space. The O-ring therefore also serves as an annular sealing element and can separate the two sub-spaces from one another in a fluid-tight manner.This prevents an exchange of gases between the electric machine 12 and the converter 11, which is advantageous for the function of the electric drive 10, as this can increase the safety of the electric drive 10. Furthermore, at least one subchamber can be filled with a potting compound; thus, all subchambers can also be filled with a potting compound. The potting compound can be thermally conductive and electrically insulating and can create a thermal coupling with an end shield of the electric drive. The end shield can be a part or a plane of the not shown. Fig. 4illustrated elements of the electric drive 10, through whose opening the phase connection 22 extends. The thermal coupling of the phase connection 22 to the bearing shield can dissipate heat from the phase connection 22 into the bearing shield and thus cool the phase connection 22. For this purpose, the bearing shield can also be passively or actively cooled, or it can simply serve as a heat buffer. In addition to minimizing the effects of vibrations or movements on the position of the phase connection 22, this can also reduce thermal expansion and slight positional changes of the phase connection 22 caused by this expansion, whereby the measuring accuracy of the magnetic core-less magnetic field sensor can be further increased. In addition, the encapsulation further mechanically fixes the phase connection 22 in the openings or the space through which the phase connection 22 extends.

[0064] Alternatively or in addition to the thermal coupling with the bearing plate of an electric drive 10, the encapsulation can also establish a thermal coupling with a heat sink of the electric drive. In this embodiment, the thermal coupling through the encapsulation is designed identically to the above-described form of thermal coupling with a bearing plate, so that the preceding aspects can also apply to the heat sink, through whose opening the phase connection 22 can extend accordingly. Whether the phase connection 22 is thermally coupled with the bearing plate or with the heat sink by the encapsulation, it is not absolutely necessary for the phase connection 22 to pass through a tunnel-shaped opening.Instead, it is necessary that the phase connection runs at least partially along a surface of the bearing shield or the heat sink, so that a contact surface is present as an interface for heat transfer between these components, which automatically entails a certain degree of mechanical fixation.

[0065] Although the term "potting" is used above, the potting does not necessarily have to be produced by casting a material described above. The potting can also be produced by other suitable manufacturing methods that can achieve thermal coupling, as described above, between the phase connection 22 and the bearing shield and / or the heat sink.

[0066] In addition, Fig. 4It can be seen that in addition to a phase connection 22 and an assembly 25, further such phase connections and assemblies can be arranged adjacent to supply further phase current branches of the electric drive, as previously described. Furthermore, the curvature 24 of the phase connection 22 is shown from a different perspective. Thus, the curved course of the phase connection 22 is better visible at the curvature 24, which in this embodiment is provided on both the left and right side and which can thus be designed as a taper of the phase connection 22. Deviating from this embodiment, the semiconductor switches of the assembly 25 can, however, also be arranged at a different location on the converter 11. Likewise, as previously described, the phase connection 22 can be designed differently and have a curvature at a different location. In one embodiment, above the Fig. 4shown level, a further level of the converter 11 is arranged, which comprises a circuit board, as in Fig. 5 shown.

[0067] Fig. 5 shows a perspective view of part of a converter 11 of an electric drive 10 with a phase connection 22. In one embodiment, the converter 11 can have a circuit board 51, as previously described. Electronic components that serve to control the converter 11 can be arranged on this circuit board. In addition, a magnetic field sensor 50 without a magnetic core can be arranged on the circuit board 51. In one embodiment, the sensor can be arranged above the curve 24 on the circuit board 51. As a result, the sensor is located in the area of ​​the curve 24, so that it can measure the magnetic field of the phase connection 22 that is amplified by the curve 24. As shown in Fig. 5As shown, the magnetic core-less magnetic field sensor 50 can be designed as a surface-mounted component, also referred to as an SMD or surface-mounted device, which is arranged as an integrated circuit in its own housing on the circuit board 51. Such a surface-mounted component can be attached to the circuit board 51 fully automatically during production, which leads to time and cost savings in production. However, the magnetic core-less magnetic field sensor 50 can also be designed as a wired electronic component, which is arranged as an integrated circuit in its own housing on the circuit board 51. Such a wired electronic component can be arranged on the circuit board 51 by plug-in mounting, also referred to as through-hole mounting or through-hole technology, which is, however, more complex and cost-intensive than a surface-mounted component.

[0068] The use of a magnetic coreless magnetic field sensor 50 on the circuit board 51 simplifies the design compared to a magnetic core-based magnetic field sensor because, apart from the simple mounting of the sensor on the circuit board 51, no further wiring or connection leading away from the sensor is required. Apart from the one physical connection to the circuit board, which is understood to be the mechanical and electrical connection of the sensor to the circuit board via one or more physical contacts, such as contact pins or wires, such a sensor therefore comprises no further terminals or connections. In particular, such a sensor does not comprise a physical connection coupling the sensor to a magnetic core. This avoids losses that would otherwise occur at other terminals, connections, or components, thereby advantageously increasing system efficiency.

[0069] Regardless of whether the coreless magnetic field sensor 50 is a surface-mounted or through-hole electronic component, the sensor may be one of the following types of sensors familiar to those skilled in the art. It may be a Hall sensor and / or a closed-loop sensor or an open-loop sensor and / or one of a magnetoresistive sensor, an anisotropic magnetoresistive effect (AMR) sensor, a giant magnetoresistive (GMR) sensor, a tunneling magnetic resistance (TMR) sensor, or a colossal magnetic resistance (CMR) sensor. This list is not intended to be limiting but merely to clarify which types of sensors are suitable for use as the coreless magnetic field sensor 50.

[0070] In addition to a magnetic field sensor, the electric drive 10 may also comprise at least one acceleration sensor, which can be used to measure vibrations or movements to which the electric drive 10 is exposed.

[0071] In one embodiment, the converter 11 may have an architecture with at least three levels that extend orthogonally to the rotational axis of the rotor of the electric machine and that are offset from one another in the direction of the rotational axis. The converter 11 may comprise a first level, wherein a circuit board 51 for controlling the converter 11 is arranged on the first level, as shown in Fig. 5shown. In one embodiment, the at least one magnetic core-less magnetic field sensor 50 can be arranged on this circuit board. In one embodiment, the converter 11 can also have a second level, wherein at least one semiconductor switch of the converter 11 is arranged on the second level. The assembly 25 can therefore be arranged on the second level. For example, the section of the phase connection 22, which extends at least partially in a plane in which the normal to the axis of rotation runs, can also be arranged on the second level. In one embodiment, the converter 11 can have a third level, wherein at least one heat sink for cooling the semiconductor switches is arranged on the third level. In addition, the third level can have a DC connection with a negative pole and the second level can have a DC voltage connection with a positive pole.These poles can be used to supply DC current to the converter 11.

[0072] Furthermore, the converter 11 can alternatively have a fourth level, wherein the fourth level has a DC voltage connection consisting of both a positive pole and a negative pole, wherein the section of the phase connection 22 that extends at least partially in a plane in which the normal to the rotation axis runs is then also arranged on the fourth level. Furthermore, the fourth level can comprise the section of the phase connection 22 that extends at least partially in a plane in which the normal to the rotation axis runs, arranged on the fourth level. Then, the third level can comprise a DC voltage connection with a negative pole and the second level a DC voltage connection with a positive pole.As previously described, the magnetic-coreless magnetic field sensor 50 can be arranged both on the circuit board 51 for controlling the converter 11 and on a current measurement circuit board that has a data-transmitting connection to the circuit board 51 for controlling the converter 11. Accordingly, the magnetic-coreless magnetic field sensor 50 can be arranged on a previously described level of the converter 11 that includes the circuit board 51, or the magnetic field sensor 50 can be arranged outside one of the levels of the converter 11. Thus, the electric drive can also comprise more circuit boards than just the circuit board 51.

[0073] Deviating from this, the elements previously described as being arranged on one of the three or four levels can, however, be arranged on only two or even just one level. This enables a particularly compact converter architecture. To reduce the levels, recesses in the components used, or multi-layered components, i.e., components arranged one above the other, can be used. However, the exact converter architecture is not decisive for the present invention, so that the elements described here and in Fig. 4 and 5 The variants shown are for illustrative purposes only.

[0074] Although the preceding description mostly refers to a single coreless magnetic field sensor 50, more than one single coreless magnetic field sensor 50 can also be used in the electric drive 10. This is because, as described, the electric drive 10 can have multiple phase current branches and phase connections. This is because each phase connection can have multiple bends, each of which can accommodate a single coreless magnetic field sensor 50. List of reference symbols:

[0075] 10Electric drive 11Converter 12Electric machine 13Connection box 14Cable 15Housing 16Motor casing 20Stator 21Slot bar 22Phase connection 23Slot 24Bend 25Assembly 32Flexible section 50Coreless magnetic field sensor 51PCB

Claims

1. An electric drive (10) comprising: - an inverter (11); - an electric machine (12) comprising a plurality of phase current branches, wherein the electric machine (12) and the inverter (11) are arranged together in a housing (15); and - at least one magnetic field sensor (50) without a magnetic core for measuring a current of at least one of the plurality of phase current branches; characterized in that at least one phase current branch of the plurality of phase current branches comprises a slot bar (21) which is arranged at least partially in a slot (23) of the electric machine (12) and which forms a phase terminal (22) outside the slot (23); and the phase terminal (22) has a curvature (24, 32) in the region of which the at least one magnetic field sensor (50) without a magnetic core is arranged.

2. Electric drive according to claim 1, wherein the phase terminal (22) extends at least partially in a plane normal to an axis of rotation of a rotor of the electric drive (10); and / or wherein the phase terminal (22) is curved away from a direction normal to the axis of rotation within the plane.

3. Electric drive (10) according to one of the preceding claims, wherein the at least one magnetic field sensor (50) without a magnetic core is arranged on a circuit board (51).

4. Electric drive (10) according to claim 3, wherein the at least one magnetic field sensor (50) without a magnetic core has only one physical connection which consists of one or more physical contacts; and wherein the one physical connection connects the at least one magnetic field sensor (50) without a magnetic core only to the circuit board (51).

5. Electric drive (10) according to one of claims 3 and 4, wherein the at least one magnetic field sensor (50) without a magnetic core consists of a surface-mounted component which is arranged as an integrated circuit in a separate housing on the circuit board (51); or the at least one magnetic field sensor (50) without a magnetic core consists of a wired component which is arranged as an integrated circuit in a separate housing on the circuit board (51).

6. Electric drive (10) according to one of claims 3 to 5, wherein the phase terminal (22) extends at least partially parallel to a plane on which the circuit board (51) is arranged.

7. Electric drive (10) according to one of claims 3 to 6, wherein the circuit board (51) is a circuit board for controlling the converter (11).

8. Electric drive (10) according to one of claims 3 to 5, wherein the circuit board is a circuit board for current measurement which has a signal-transmitting connection to a circuit board (51) for controlling the converter (11).

9. Electric drive (10) according to one of the preceding claims, wherein the at least one magnetic field sensor (50) without a magnetic core is a Hall sensor and / or one of a closed-loop sensor or an open-loop sensor and / or one of a magnetoresistive sensor, an anisotropic magnetoresistive effect, AMR, sensor, a giant magnetoresistance, GMR, sensor, a magnetic tunnel resistance, TMR, sensor or a colossal magnetic resistance, CMR, sensor.

10. Electric drive (10) according to one of the preceding claims, wherein the phase terminal (22) further comprises a flexible portion (32) with a curved shape which connects the phase terminal (22) to the part of the slot bar (21) which is arranged at least partially in the slot (23) of the electric machine (12) and which is mechanically flexible at least in a direction of an axis of rotation of a rotor of the electric machine (12) in order to be able to compensate mechanical stresses occurring at least in the direction of the axis of rotation.

11. Electric drive (10) according to claim 10, wherein the at least one magnetic field sensor (50) without a magnetic core for measuring the current of at least one of the plurality of phase current branches is arranged at the flexible portion (32) and in the region of the curved shape of the flexible portion (32).

12. Electric drive (10) according to one of claims 10 and 11, wherein the flexible portion (32) extends orthogonally to the direction of the axis of rotation and wherein the curved shape of the flexible portion (32) has a U-shape.

13. Electric drive (10) according to one of the preceding claims, wherein an O-ring encloses the phase terminal (22) and divides a space located around the phase terminal (22) into two sub-spaces and separates them from each other in a fluid-tight manner.

14. Electric drive (10) according to claim 13, wherein at least one of the sub-spaces is filled with a casting; and the casting is thermally conductive and electrically insulating; and the casting is thermally coupled to a bearing shield and / or a heat sink of the electric drive (10).

15. Electric drive (10) according to one of the preceding claims, wherein the electric drive (10) additionally comprises an acceleration sensor.