DE102017006127A1 - Avionics or automotive powertrain with electric machine - Google Patents

Abstract

An avionics or automotive powertrain has an electric machine having a stator and a rotor rotatable relative to the stator, the stator having one or more stator windings and the rotor having one or more rotor windings, and the stator a first, with the stator associated with fixed transformer winding, which is magnetically coupled to a second, rotatable with the rotor transformer winding, wherein the first transformer winding and the second transformer winding for transmitting energy from the first to the second transformer winding via a gap therebetween are arranged, and wherein the second transformer winding with the input side of a rectifier stage connected downstream of the transformer winding is electrically connected, whose output side is electrically connected to one or more of the rotor windings in order to supply them with a secondary exciter current.

Description

introduction

Here is an avionics or automotive powertrain with electric machine described, and such an electric machine. Details are defined in the claims; The description and the drawing also contain relevant information on the powertrain and how it works as well as the electrical machine and its variants.

Technical background

An electric machine is understood to be an electric machine in the form of an internal or external rotor machine. An electric machine can be both an electric motor and an electric generator. Currently, up to several hundred kilowatts of permanent-magnet electric machines are often used in avionics or automotive applications in the powertrain. However, these are relatively expensive due to the rare earth permanent magnets (NdFeB, SmCo, etc) installed therein. As advantages of the permanent magnet excitation against the electrical excitation apply: smaller outer diameter at the same nominal power, lower volume and weight at the same nominal power, simpler structure, higher efficiency, since no pathogen losses, less expensive production, better dynamics because no pathogen field structure.

However, the availability of rare-earth permanent magnet material is limited and thus limits its use on a large scale in avionics or automotive applications. Other approaches in avionics or automotive applications rely on asynchronous machines in which the excitation energy is fed into the rotor by means of brush-slip ring assemblies.

Currently, for example, different electric motors are used in automotive applications depending on the purpose of the vehicle. The system costs, the available space, required functions and the efficiency play a role. So far, in automotive applications mainly asynchronous and permanent magnet synchronous machines are used. Asynchronous machines are very robust and cost-effective. Permanently excited synchronous machines are by their comparatively short length preferably for direct integration into the transmission bell of the drive train. They offer high efficiency and are often used in mild and full hybrid models. For example, a 60 kW synchronous machine is used as the electric motor / generator in newer models of the Toyota Prius, and the ZF AG offers under the designation SG 325 L 32 a permanent-magnet synchronous machine for a 12 kW parallel hybrid drive.

Underlying problem

For electromobility applications in the avionics or automotive sector, a cost-effective and reliable powertrain with an electric machine is to be proposed.

Suggested solution

To solve the problem, an avionics or automotive powertrain having an electric machine is proposed which comprises a stator and a rotor rotatable relative to the stator, the stator having one or more stator windings and the rotor having one or more rotor windings, and a first stator , associated with the stator fixed transformer winding, which is magnetically coupled to a second, rotatable with the rotor transformer winding, wherein the first transformer winding and the second transformer winding are arranged for transmitting energy from the first to the second transformer winding via a gap between them, and wherein the second transformer winding is electrically connected to the input side of a rectifier stage connected downstream of the transformer winding, the output side of which is electrically connected to one or more of the rotor windings in order to connect them to a secondary winding n excitation current to feed.

In an avionics or automotive powertrain having such a separately excited electrical machine, on the one hand power is supplied to the stator and, on the other hand, the rotor is supplied with electrical excitation energy. In a separately excited (DC) machine stator and (rotor) excitation winding are fed from different voltage sources.

This is in contrast to see about to a permanent-magnet electric machine in which the rotor is equipped with permanent magnets whose magnetic field - in the engine operation case - interacts with the caused by the stator current magnetic field, so as to cause a rotation of the rotor; In the generator operating case, a rotation of the rotor causes a tappable at the terminals of the stator winding electrical power.

The arrangement presented here offers an avionics or automotive powertrain for the mass market of electromobility. This powertrain comes without expensive and hard to get Rare-earth permanent magnets in the electric machine off; This powertrain is also low-wear, durable and efficient to operate. In particular, in pure electric drive high efficiency over a wide range of torque and speed can be achieved, which allows efficient use of the battery.

From the power plant construction, although foreign-excited machines are known in which on the generator shaft, an exciter generator brushless is fed with electrical excitation energy. For example, three-phase synchronous generators are used to generate electrical energy and in large power plants. Here, the stator windings are designed either as a concentrated or distributed winding. Three windings offset by 120 ° around the circumference serve to generate a rotating magnetic field. The stator windings are traversed by three sinusoidal currents phase-shifted by 120 °. On the runner an electromagnet is applied. The power supply of the electromagnet is usually via slip rings or brushless on the exciter generator. If the rotor and the stator field have no relative speed to one another, ie are synchronous, a torque with a mean value not equal to zero can be formed. The angle between rotor and stator field is decisive for the amount of torque. Although the externally excited synchronous machine is a robust machine type with a good efficiency and a good power density. However, these large power station assemblies are not transferable as drives to an avionics or automotive powertrain for the mass market of electric mobility. Conventional DC machines also generate a so-called brush fire on their brushes, which is the main cause of high-frequency interference. This brush fire also limits the maximum speed since the brushes get hot at high speeds and wear very quickly. Furthermore, high speeds cause higher induction voltages, which can lead to the surrounding brush fire.

The avionics or automotive powertrain of the type disclosed herein avoids the disadvantages of a slip ring transmitter and uses non-contact transmission for the excitation energy of the (rotor) field winding. This non-contact transmission is designed much simpler than the known excitation generators. This transmission is realized by an annular transformer or transformer, one side of which is designed to rotate. The fixed primary side of the transformer can be fed by a pulse width modulated half or full bridge circuit. The rotating secondary side of the transformer can feed the exciter winding via a rectifier circuit. By a correspondingly high selected transmission frequency, the transmission can be made very compact. When using ferrite material in the transmission cores of the transformer, a transmission frequency greater than 100kHz can be selected. Thus, on the one hand avoided the wear and speed-dependent contact resistance afflicted slip rings and on the other hand, the complex and very much space-consuming excitation generators needed. In an internal rotor, the transformer can be arranged axially next to the stator and radially below the winding head of the stator. On the rotor side of the exciter current is rectified by means of diodes.

In a variant of the drive train presented here, the first and second transformer windings are assigned to a respective first and second soft-magnetic transmission core.

In a further variant of the drive train, the first and second soft-magnetic transmission cores are magnetically coupled and contain ferrite-containing material.

In a further variant of the drive train, the first and second soft-magnetic transmission cores together with the first and second transformer windings form a transformer with a stationary and a rotating side, in which the two sides are located between them (circular ring-shaped or cylinder-shell-shaped ) Gap are separated.

In a further variant of the drive train mutually facing mantle or end faces of the two sides of the transformer are each structured with a corresponding relief, for example in the form of alternating webs and grooves. This causes a repetitive change in reluctance, depending on the degree to which the lands and grooves are aligned. This repetitive reluctance change results in a similar amount of current consumption of the first and second transformer windings. This fluctuating current consumption can be evaluated for determining the position of the rotor by means of a not further illustrated evaluation.

In a further variant of the drive train, the first transformer winding is electrically connected to an exciter circuit, which is set up to feed the first transformer winding with a primary exciter current.

In a further variant of the drive train, the excitation circuit is configured to supply the first transformer winding with a primary exciter current having a frequency between approximately 50 5 kHz and to vary the pulse width of the primary excitation current. The rotor temperature is determined in another, not further illustrated variant on the temperature-dependent resistance of the field winding, since a higher resistance leads to a higher voltage requirement in the primary winding. This higher voltage requirement can be achieved via the duty cycle in the pulse width modulation by the excitation circuit 60 be determined. The transmission of other signals is possible by modulation or superposition of the secondary voltage.

list of figures

Other objects, features, advantages and applications will be apparent from the following description of non-limiting embodiments to be understood with reference to the accompanying drawings. All the described and / or illustrated features alone or in any combination show the subject matter disclosed herein, also irrespective of their grouping in the claims or their relationships. The dimensions and proportions of the components shown in the figures are not necessarily to scale; they may differ from what is illustrated here in embodiments to be implemented.

• 1 eine schematische Darstellung einer Variante eines Automotive-Antriebsstrangs mit einer elektrischen Maschine,
• 2 eine erste schematische perspektivische Darstellung eines Übertragers,

Show

• 1 a schematic representation of a variant of an automotive powertrain with an electric machine,
• 2 a first schematic perspective view of a transformer,

Detailed description of the drawing

An in 1 illustrated automotive powertrain AAS has an electric machine 10 the type explained in detail below. This electric machine 10 in internal rotor execution drives over its shaft 10a a not further explained in detail differential gear Get an, whose two output shafts each have a wheel R1 . R2 set in rotation.

The electric machine 10 has a stand 12 and one relative to the stand 12 revolving runner 14 , where the rotatable runner 14 , being on the shaft 10a the electric machine 10 rotatably seated. The stand 12 has at its periphery distributed in not further illustrated coaxially oriented grooves a plurality of stator windings 22 that have connections r . s . t be fed with electrical rated power. The runner 14 has also distributed on its circumference in not further illustrated coaxially oriented grooves a plurality of rotor windings 24 , The electric machine 10 has a housing 10b, in which the wave 10a is stored stored at the two ends. In the case 10b is, a first, with the stand 12 fixed transformer winding 32 arranged. This fixed transformer winding 32 is with a second transformer winding 34 magnetically coupled with the runner 14 on the wave 10a is arranged and thus relative to the fixed transformer winding 32 is rotatable.

In the variant shown here is to supply a field voltage UF to the rotor windings 24 one the first transformer winding 32 with a field circuit 60 electrically connected, which is adapted to the first transformer winding 32 to feed with a primary excitation current. This is provided by the exciter circuit 60 four clock signals a ... d, each one (semiconductor) switch S1 ... S4 a full bridge circuit VBS drive. In the middle of the full bridge circuit VBS is the bridge branch, here with the first, with the stand 12 fixed transformer winding 32 is occupied. The arrangement allows a polarity change of the transformer winding 32 applied voltage.

The exciter circuit 60 provides a variable clock pattern as clock signals a ... d around the first transformer winding 32 with a primary excitation current having a frequency between about 50 kHz and about 5 MHz and to vary the pulse width of the primary excitation current. So serve the first transformer winding 32 and the second transformer winding 34 are used to transfer energy from excitation energy to the electric machine 10 to operate as a foreign-excited machine. The excitation energy from the first to the second transformer winding 32 . 34 over an air gap between them 36 transfer. In the in 1 illustrate variant are the first transformer winding 32 and the second transformer winding 34 designed as toroidal coils and in each case in a respective annular cylindrical first and second soft magnetic transmission core 52 . 54 added. The first and second soft magnetic transmission cores 52 . 54 form here together with the first and the second transformer winding 32 . 34 a transformer 50 with a standing and a rotating side, in which the two sides are separated by the gap between them 36 are separated. The annular cylindrical first and second soft magnetic transmission cores 52 . 54 of the transformer 50 are in this variant coaxial along the shaft 10a arranged so that the gap 36 between each of them a top surface of the respective annular cylindrical transmission core 52 . 54 is. See also 3 , In another, in 4 illustrated variant are the annular cylindrical transmission cores 52 . 54 arranged concentrically, so that the fixed annular cylindrical transmission core 52 lies outside and with the shaft 10a and the runner 14 rotating annular cylindrical transmission core 54 is enclosed by this. In this case, the gap has 36 of the transformer 50 the shape of the lateral surface of a circular cylinder.

The second transformer winding 34 of the transformer 50 is with an input side m, n one of the second transformer winding 34 downstream rectifier stage 40 electrically connected. This rectifier stage 40 has an exit side p . q that with the rotor windings 24 is electrically connected to feed them with a rectified secondary excitation current. The rectifier stage 40 is here as a bridge rectifier circuit with four single diodes D1 ... D4 realized the same type. In a variant not further illustrated, the second transformer winding 34 of the transformer 50 configured with one with a center tap; thus, using two single diodes, a two-pulse center point circuit is provided. M2 to realize with the same efficiency as a bridge rectifier circuit.

The transformer 50 can build very simple and so small in the variants shown here, so that the foreign-excited electric machine 10 either no or little extra space needed. The transformer 50 has no mechanical wear, as the transfer takes place without contact. As a result, the exciting current is transmitted safely and increased reliability of the machine even at very high speeds. The material used for the transformer is very low and favors economical mass production. In contrast to an excitation generator, the excitation power can be controlled in a simple and effective manner regardless of the rotational speed. Furthermore, on the transmission ratio of the transformer 50 the output voltage of the second transformer winding 34 ideal for the runner 14 be determined. Thus, an optimal wire cross-section can be chosen, which ensures a good filling factor with good windability.

The variants described above, as well as their construction and operating aspects serve merely to better understand the structure, the mode of operation and the properties; they do not restrict the revelation to the exemplary embodiments. The figures are partially schematic, wherein essential properties and effects are shown partially enlarged significantly to illustrate the functions, principles of operation, technical features and features. In this case, every mode of operation, every principle, every technical embodiment and every feature which is / are disclosed in the figures or in the text, with all claims, every feature in the text and in the other figures, other modes of operation, principles, technical embodiments and features contained in this disclosure or resulting from it, are freely and arbitrarily combined, so that all conceivable combinations of the variants described are assigned. In this case, combinations between all individual versions in the text, that is to say in every section of the description, in the claims and also combinations between different variants in the text, in the claims and in the figures. Also, the claims do not limit the disclosure and thus the combination options of all identified features with each other. All disclosed features are also explicitly disclosed individually and in combination with all other features herein.

Claims (7)

An avionics or automotive powertrain (AAS) with an electric machine (10) - a stand (12) and - A relative to the stator (12) rotatable rotor (14), wherein - The stator (12) has one or more stator windings (22), and - The rotor (14) has one or more rotor windings (24), and - The stator (12) is associated with a first, with the stator (12) fixed transformer winding (32) with - A second, with the rotor (14) rotatable transformer winding (34) is magnetically coupled, wherein - The first transformer winding (32) and the second transformer winding (34) for transmitting energy from the first to the second transformer winding (32, 34) via a gap between them (36) are arranged, and wherein - The second transformer winding (34) with an input side (m, n) of the second transformer winding (34) downstream rectifier stage (40) is electrically connected, and - The rectifier stage (40) has an output side (p, q) which is electrically connected to one or more of the rotor windings (24) in order to feed them with a secondary excitation current. The avionics or automotive powertrain (AAS) with an electric machine (10), after Claim 1 wherein the first and second transformer windings (32, 34) are associated with respective first and second soft magnetic transmission cores (52, 54). The avionics or automotive powertrain with an electric machine (10), after Claim 2 in which the first and second soft magnetic Transmission cores (52, 54) are magnetically coupled and contain ferrite-containing material. The avionics or automotive powertrain with an electric machine (10), after one of Claims 1 to 3 wherein the first and second soft magnetic transmission cores (52, 54) together with the first and second transformer windings (32, 34) form a transmitter (50) having a standing and a rotating side, in which the two sides intersect located gap (36) are separated. The avionics or automotive powertrain with an electric machine (10), after Claim 4 in which mutually facing, the gap (36) delimiting surfaces (56, 58) of the two sides of the transformer (50) in each case with a corresponding relief (56a, 58a) are structured. The avionics or automotive powertrain having an electrical machine (10), wherein the first transformer winding (32) is electrically connected to an exciter circuit (60) configured to feed the first transformer winding (32) with a primary energizing current , The avionics or automotive powertrain with an electric machine (10), after Claim 6 in that the energizing circuit (60) is arranged to feed the first transformer winding (32) with a primary exciting current having a frequency between about 50 kHz and about 5 MHz and to vary the pulse width of the primary exciting current.

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