DE102018124784A1 - Stator of an electric motor and charging device, in particular with such a stator - Google Patents

Abstract

The invention relates to a stator for an electric traction motor of a motor vehicle, with a stator jacket and one or more groups of at least three conductor strands for generating a magnetic field. The at least three conductor strands have a star point and each conductor strand is designed as a stator winding for one phase. The stator jacket has a multiplicity of concentrically arranged and spaced-apart stator slots. In order to avoid uneven heating and / or inductance of the stator, each conductor strand in the plurality of stator slots is alternately arranged in a predetermined pattern in such a way that a wave winding is formed. Likewise, a charging device for DC charging a vehicle battery is provided, the inductance of which is formed by a wave winding in a stator.

Description

The invention relates to a stator of an electric motor and a charging device for charging a battery of a motor vehicle designed with an electric traction motor or electric motor designed for drive operation, generator operation and DC charging operation.

Different charging concepts are used to charge electric vehicles. Charging with alternating current via the house socket is available almost everywhere, but only has a low charging power of less than 5 kW. In contrast, much faster outputs (50 kW and above) are possible with fast charging at DC sources (DC charging / DC charging mode), for example via special charging stations. However, this requires adjustment if the available voltage level of the charging station, e.g. 400 V DC, and the voltage level of the vehicle battery, e.g. 800V DC, fall apart.

• EP 2 527 186 A2 zeigt eine Ladeschaltung unter Nutzung der Motorinduktivitäten. Das System weist einen Gleichrichter auf, der Energie von einem externen Versorgungsnetz an einen Eingang liefert, und einen Antriebsinverter, dessen Wechselspannungsseite mit Phasenwicklungen einer Induktionsmaschine verbunden ist. Ein Strompfadabschnitt leitet den von dem Gleichrichter gelieferten Strom zu dem System. Der Abschnitt weist einen steuerbaren Leistungsschalter zum selektiven Unterbrechen des Abschnitts auf, wobei das System als Hochsetzsteller und Tiefsetzsteller in Richtung eines Energiespeichers mittels des Schalters und der Wicklungen arbeitet.

To adjust the voltage level, step-up converters, also known under the terms “step-up converter”, “boost converter” or “step-up converter”, can be used as separate units. However, it is also possible to use an already existing inverter (also referred to as “inverter” in English) of the traction or electric motor as a step-up converter for DC voltage conversion. In order not to have to use additional inductors for the step-up position in the inverter, it is known that it is possible to use the windings of the traction motor as charging inductors:

• EP 2 527 186 A2 shows a charging circuit using the motor inductors. The system has a rectifier, which supplies energy from an external supply network to an input, and a drive inverter, the AC voltage side of which is connected to phase windings of an induction machine. A current path section directs the current supplied by the rectifier to the system. The section has a controllable circuit breaker for selectively interrupting the section, the system working as a step-up converter and step-down converter in the direction of an energy store by means of the switch and the windings.

A stator usually comprises an electrical winding for generating a magnetic field, the winding being excited with multi-phase current (three-phase). A stator winding has winding parts for each phase ( U , V , W ) to (phase winding), which are connected in a triangular or star arrangement. If phases are connected to a star point, the phase windings run from the phase connection of a phase ( U ; V ; W ) to the star point. A phase can be divided into several sub-phases (U> U1, U2), each sub-phase being designed as a winding ( U1 , U2 , ...; W1 , W2 , ..., V1 , V2 , ...), which may or may not be connected. A winding part that consists of the conductors of the same partial phase ( U1 , W1 , V1 ) exists, can also be addressed as a winding set or parallel group.

Since winding parts are sometimes addressed differently, the following terms are defined: A phase strand is a conductor strand of a phase winding. If phases are connected to a star point, a phase strand is a conductor strand between a phase connection and a star point. If phases are connected in a delta connection, a phase strand is a conductor strand between two phase connections. A conductor line can basically branch into several parallel and / or serial sub-lines.

A phase group is the sum of all conductor strands of the same phase or partial phase ( U respectively. U1 , U2 , ...). Parallel phase strands are formed by parallel strands of the same phase ( U1 , U2 ). They can have a common star point or separate star points. Otherwise, a group is any multitude of leaders who are grouped according to a certain scheme.

A coil winding is a type of winding in which conductor strands in the form of single or multiple closed coils or loops are guided through a stator laminated core.

It is the task of specifying an improved electric traction motor in which a DC charging operation is made possible and the motor winding serves as inductors of a step-up converter.

For this purpose, a stator according to claim 1 is provided according to the invention. It is in particular a stator for an electric traction motor of a motor vehicle, with a laminated core and one or more groups of at least three conductor strands for generating a magnetic field, the at least three conductor strands of a group having at least one common star point and each conductor strand as a stator winding for one Phase is designed (phase strand). The laminated core in this case has a multiplicity of concentrically arranged and spaced-apart stator slots, each conductor strand in the multiplicity of stator slots being alternately arranged in a predetermined pattern in such a way that a wave winding is formed. The laminated core is e.g. constructed from individual sheet metal lamellas made and stacked from electrical sheet.

To display the traction motor, a rotor is arranged in the stator, which rotates about an axis of rotation which coincides with a stator axis.

In contrast to a coil or loop winding, a wave winding is characterized in that it can be arranged in a wave-like and / or meandering manner around the stator axis, in particular along a stator circumference, of the stator. The phase strand runs through a stator slot in one direction, skips a certain number of stator slots in one angular direction, runs through the next stator slot in the opposite direction, again skips a certain number of stator slots in the same angular direction, and so on; until the phase strand has described one or more integer round trips. Rotation means the geometrical orbiting of the axis of the stator (stator axis) along the stator slots seen on the face.

The sections of the conductor strands that run through the stator slots can in particular be arranged concentrically around the axis of the stator; ie parallel to each other and to the axis of the stator. When the stator laminated core is unwound, a wave winding is represented as a rectangular function / oscillation or a similar meandering shape. It can be viewed as a sequence of successive half-coils, the half-coils being formed alternately on one side of the winding head and then on the other.
The advantage of the wave winding is that the wave winding, compared to the coil winding, is less sensitive to external influences in its electrical and / or magnetic behavior in the traction motor. For example, the inductances of the individual phase windings or strands are only subjected to comparatively minor changes in the case of geometric misalignments, such as, for example, an inclined position of the rotor relative to the stator. Since the inductances of the individual phase windings or strands are of the same size during a charging operation, the same currents flow through all phase windings or strands. There are therefore essentially no equalizing currents between the strands.

In the case of a coil winding, an inclined position of the rotor would lead to different inductances and thus to different charging currents per phase. This would require equalizing currents between the strands; this is disadvantageous.

In an advantageous embodiment, the stator has a plurality of parallel groups of conductor strands, each group having its own star point. Several or all star points can be electrically connected to each other. The electrical connection is advantageously made via isolating switches.

Connectable means that the star points have a first state in which the star points are electrically connected to one another and a second state in which the star points are electrically separated from one another. The process can take place, for example, via circuit breakers, in particular contactors or relays. Depending on the number of star points, only two, more than two or even all star points can be connected to one another.

The term “parallel groups” is understood to mean parallel stator winding groups, each of which has a conductor arrangement with at least one phase per phase. All phase strings in a group are each interconnected in their own star point. The electrical and magnetic properties of the stator can be advantageously influenced by connecting or disconnecting the star points.

The term winding set is synonymous with parallel stator winding group. The stator can have one or more winding sets. A winding set is to be understood in accordance with the introductory definition.
The stator can have one or more star points. In particular, the stator according to the invention in various configurations can advantageously be set up for charging operation.

By using a wave winding versus a coil winding, uneven heating of the stator can be reduced for cases in which only parts of the phase winding, e.g. only one winding set can be used.

In an advantageous embodiment, the stator has only one winding set comprising three phase strands, the phase strands having no parallel subgroups. This enables a simple construction.

• Wellenwicklungen besitzen mindestens einen Sternpunkt, in welchem einzelne Phasenstränge verschalten sind. Für eine große Flexibilität bei der Auslegung von Traktionsmotoren werden Wicklungsmuster mit genau einem Sternpunkt kaum in Erwägung gezogen. Ein Sternpunkt schränkt die Auswahl an möglichen Wicklungsmustern stark ein und kann für die Optimierung der Leistung im Antriebsbetrieb nachteilig sein. Grundsätzlich sind mehrere Sternpunkte zu bevorzugen. Mehrere Sternpunkte erlauben eine größere Variabilität an Wicklungsmustern, insbesondere im Hinblick auf Windungszahlen. Sie eignen sich insbesondere für parallele Gruppen mit einem Sternpunkt je Gruppe, beispielsweise für Hairpin-Wicklungen. Im Ladebetrieb sind parallele Gruppen für einen Ladebetrieb jedoch nachteilig, da die parallelen Gruppen unterschiedliche Induktivitäten aufweisen können. Ursache für unterschiedliche Induktivitäten können ungleiche Verteilungen der verschiedenen Wicklungen über den Statorumfang sein. Beispielsweise kann dies bewirkt werden durch unterschiedliche Verteilung der Leiter in einem Mehrlagensystem. Dies würde in einem Ladebetrieb zu unterschiedlichen Ladeströmen und damit zu Ausgleichsströmen innerhalb bzw. zwischen einzelnen Gruppen führen.

The advantages are offset by disadvantages:

• Wave windings have at least one star point in which individual phase strands are connected. For great flexibility in the design of traction motors, winding patterns with exactly one star point are hardly considered. A star point severely limits the choice of possible winding patterns and can be disadvantageous for optimizing the performance in drive operation. In principle, several star points are preferred. Multiple star points allow greater variability Winding patterns, especially with regard to the number of turns. They are particularly suitable for parallel groups with one star point per group, for example for hairpin windings. In charging operation, however, parallel groups are disadvantageous for charging operation, since the parallel groups can have different inductances. Different inductances can be caused by uneven distributions of the different windings over the circumference of the stator. For example, this can be achieved by different distribution of the conductors in a multi-layer system. This would lead to different charging currents in a charging operation and thus to equalizing currents within or between individual groups.

Furthermore, the charging current is limited by the accumulated copper cross-section of all strands, since each conductor / conductor strand may only be subjected to a maximum permissible current.

If only one star point is used during charging, the permissible charging current is limited to the phase strings connected to the star point (use of only one of the parallel groups). If several star points (ie several parallel groups) are used in charging mode, the max. permissible charging current is higher, however the star points must be interconnected so that they can be connected to a charging source. Interconnecting the star points is technically very complex (additional high-current contactors are required). When driving, the parallel groups must be separated, otherwise circulating currents flow and high copper losses occur.
Furthermore, it is an object of the present invention to provide an improved charging device for a DC charging operation of a vehicle battery. In a first aspect, the aim is to specify a charging device that can implement high charging currents. In a second aspect, the aim is to specify a charging device which is highly efficient. In yet another aspect, the aim is to provide a loading device that is easy to manufacture.

For this purpose, a charging device according to claim 3 is specified according to the invention. This charging device for charging a battery of a motor vehicle designed with an electric traction motor designed for drive operation, generator operation and DC charging operation has an inductance and a drive converter. The drive converter is designed to convert the DC voltage of the battery for the electric traction motor in the drive mode of the motor vehicle or to rectify an AC voltage for charging the battery in generator mode. The inductance, together with the drive converter, serves as a step-up converter for a DC charging operation of the battery, the inductance comprising winding parts of a stator winding of the electric traction motor. The stator winding is designed as a wave winding.
The traction motor is preferably controlled by circuit breakers which are connected in a half-bridge circuit in order to represent a corresponding torque control. The circuit breakers are controlled by a corresponding control. The entire assembly is referred to as the drive converter. However, it is also conceivable and possible to represent the circuit breakers in a full bridge circuit. The invention is applicable to both types of connection. Other designs for switching the drive converter are conceivable and possible.

In an advantageous embodiment, the charging device has an electric traction motor with a stator according to the invention, in particular according to claim 1 or 2.

In one embodiment, at least two, preferably more than two or particularly preferably all, star points of the stator winding are used for the DC charging operation. To do this, the star points are connected to each other during charging. This has the advantage that the sum of the electrical conductors used for the step-up position is variable; the charging current can be selected high. However, this has the disadvantage that the star points have to be connected to one another for DC charging operation. An electrical connection of the star points is technically very complex (additional high current contactors are necessary). Another disadvantage is that geometric errors such as skewing of the rotor or manufacturing errors cause unequal inductances and thus cause leakage currents in the form of equalizing or circulating currents in the stator winding.

In another embodiment, exactly one star point is used for the DC charging operation.

In a dependent embodiment, the stator winding has a plurality of star points, with exactly one star point being used for charging operation. This can be achieved, for example, by the fact that the star points are not electrically connected to one another during DC charging operation. This means that the charging current on a winding set (e.g. U1 , V1 , W1 ) limited; in other words: the charging current flows from a star point only via phase strands of a winding set (e.g. U1 , V1 , W1 ) to the drive converter.

This has the disadvantage that the maximum possible charging current is limited because not all winding parts are used as conductors. This is however irrelevant if a maximum charging current provided by a charging station is less than the maximum permissible current in a winding set. This applies, for example, to vehicles in the premium class: the available charging current of a charging station is, for example, 100A and the permissible phase current is, for example, 130A (this corresponds to 390A when 3 parallel lines are used). Partial use of the stator winding is therefore not a disadvantage here.
However, it is advantageous that the relative charging inductance of the winding set used is higher than the relative charging inductance when all winding sets are used, since in addition to the rotor, the stator laminated core is also decisive for the charging inductance. This enables current or voltage curves to be smoothed better and corresponding ripples to be reduced during the charging process.

However, if the charging current provided by the charging station is higher than the permissible value of a phase current, the charging power is limited to the permissible current in the winding set.
In an alternative embodiment, the stator winding has exactly one star point, with exactly one star point being used for the charging operation. This enables a maximum charging current; however, the inductance per strand is reduced, as a result of which current and / or voltage ripples and thus the power loss increase. This can be used advantageously in the medium and low-performance area, where the continuous current while driving and the charging current are of the same size.

For all the variations described so far, exactly one or two or three or more phases can advantageously be used for the DC charging operation, in particular depending on the state of charge of the battery. The winding has, for example, three phase strands; however, only the strands of one phase (e.g. U ) or partial phase ( U1 ) used. As a result, analogous to the use of only one winding set (parallel group), larger charging inductances and thus smaller current and voltage ripples can be realized than when using all phases. For this purpose, only a half bridge of the drive converter is controlled. This can improve the efficiency of charging in the final phase when the battery is almost full.

It is particularly advantageous if the number of phases used is varied during a (single) charging process. This can e.g. the ratio of charging power to power loss can advantageously be varied. The charging process preferably starts with the use of all phases and ends with the use of only one phase.

In one variant, the variable use of phases during the charging process can also be combined with the variable use of star points or parallel groups, e.g. by activating or deactivating death points.

In another aspect, in a further alternative embodiment according to the invention, it has proven to be advantageous if the stator winding has exactly one phase per phase. This means that the stator winding has no parallel groups or only one winding set. In particular, it has no parallel subgroups. This enables a high charging current to be achieved and compensating currents to be avoided.

Furthermore, the stator windings can have shaped strands. Strands are wire bundles that are connected at their ends in an electrically conductive manner. Molded strands are strands pressed into a certain cross-sectional shape. The cross-sectional shape essentially corresponds to the slot geometry of the stator. Form braids have the advantage that the losses with pulsating charging current are smaller due to the skin effect than with full copper conductors and hairpins. Furthermore, the cross-sections of segmented conductors made of stranded wire can be chosen larger than hairpins and other segmented conductors made of solid copper, without the skin effect having any adverse effects. In particular, a 2-layer winding can be implemented particularly well using stranded wires, while preferably for hairpin windings 4th to 8th Layers must be used to keep the parasitic AC losses low. By using 2-layer systems, it is advantageously possible to form shaft windings without parallel groups or with a single star point, which can be used for charging operation in the aforementioned manner.

Likewise, the stator winding can be formed from rod conductors and interconnection or connecting bars. This enables very simple assembly. In addition, the star point can be easily brought out on a winding head side using its own interconnection level, without the space requirement increasing significantly. Rod conductors are to be understood as both shaped strands (e.g. molded wire strands), hairpins (e.g. U-shaped solid copper conductors) or I-pins (e.g. rod-shaped solid copper conductors).

In a further advantageous embodiment, each strand of the stator winding surrounds the stator by an integral multiple of 360 °. The angle 360 ° is to be understood as a geometric angle around the stator axis and not as an electrical angle.

The stator winding is advantageously designed as a two-layer system. There are always two in each stator slot of a stator laminated core Conductor strands, especially one above the other, arranged; the two conductor strands can belong to the same phase strand or to two different phase strands. The charging device can additionally have a switching unit which is designed to connect a charge source or charging station to the vehicle battery directly or via the step-up converter.

This has the advantage that the charging device can be easily connected to the charge source. The charging device adapts to the properties of the charge source and enables the vehicle battery to be charged effectively without additional settings. The charge source can thus provide a lower or the same high voltage as the vehicle battery, which is connected to the charging device and ultimately to the vehicle battery by means of the switching unit in such a way that the vehicle battery can be charged.

The switching unit is preferably designed to identify a connected charge source. This can be done by the switching unit measuring the voltage of the charge source in advance and / or certain data from the charge source, e.g. wired and / or wireless, reads out. Once the charge source has been identified, depending on the identification, the charge source with the battery is e.g. directly, via the step-up converter or a step-down converter of the charging device. As a result, the charging device is able to identify the connected charge source independently and without external control and to connect / connect it to the vehicle battery. Alternatively or additionally, the switching unit can receive data, e.g. from the charge source, which identifies the charge source and / or controls the switching unit in order to connect the charge source to the vehicle battery accordingly.

In further advantageous embodiments, the drive converter is designed as a 2-level inverter or as a 3-level inverter. The 3-level inverter can in particular be designed as a neutral point clamped (NPC) or T-shape neutral point clamped (TNPC) inverter.

Furthermore, the drive converter can be designed for three voltage phases and each have a half bridge to supply each coil winding of the electric motor. However, it is conceivable and possible to control the coil windings of the electric motor with full bridges.

Preferably, one to three half bridges with corresponding inductors can be controlled and used as step-up converters for charging the battery. The step-up converter can be used individually or simultaneously, in particular with or without a phase offset. The more step-up converters in particular are operated at the same time, the higher the charging power available for the vehicle battery.

In order to save the number of components and thus the costs for the charging device, the inductance required for a step-up converter can be formed by at least one wave winding of the electric motor.

The present invention also provides an electric drive system with a charging device according to the invention.

The figures described below relate to preferred exemplary embodiments of the charging device according to the invention, these
Figures do not serve the limitation, but essentially to illustrate the invention.

• 1 eine schematische Darstellung eines Antriebssystems mit einer erfindungsgemäßen Ladevorrichtung;
• 2 eine schematische Darstellung eines zweiten Antriebssystems mit einer erfindungsgemäßen Ladevorrichtung;
• 3 eine weitere schematische Darstellung des zweiten Antriebssystems gemäß 2;
• 4 eine schematische Darstellung eines dritten Antriebssystems mit einer erfindungsgemäßen Ladevorrichtung;
• 5a eine schematische Darstellung einer dreiphasigen Wellenwicklung eines erfindungsgemäßen Stators;
• 5b eine schematische Darstellung eines mehrfachen Umlaufs einer Wellenwicklung
• 6a eine Seitenansicht auf ein Statorblechpaket als Statormantel mit beispielhaft eingeschobenen Stableitern;
• 6b eine Querschnittsansicht auf das Statorblechpaket gemäß 6a;
• 7 einen als Formlitze ausgebildeten Segmentleiter/Stableiter;
• 8 ein bevorzugtes Verschaltungsschema einer dreiphasigen Wellenwicklung; und

Show it

• 1 a schematic representation of a drive system with a charging device according to the invention;
• 2nd a schematic representation of a second drive system with a loading device according to the invention;
• 3rd a further schematic representation of the second drive system according to 2nd ;
• 4th a schematic representation of a third drive system with a charging device according to the invention;
• 5a is a schematic representation of a three-phase wave winding of a stator according to the invention;
• 5b is a schematic representation of a multiple revolution of a wave winding
• 6a a side view of a stator laminated core as a stator jacket with inserted rod conductors;
• 6b a cross-sectional view of the stator core according 6a ;
• 7 a segment conductor / rod conductor designed as a stranded wire;
• 8th a preferred circuit diagram of a three-phase wave winding; and

1 shows a schematic representation of a drive system 1 with a loading device according to the invention. The drive system 1 has a housing 13 on in which an electric motor 2nd , a Inverters or drive inverters 3rd , a switching unit 10th and an axle drive device 11 are arranged. The electric motor 2nd has two groups of stator windings (synonymous with two winding sets): the first group has the stator windings U1 , V1 and W1 as phase strands at the first star point 6a are interconnected, and the second group has the stator windings U2 , V2 and W2 as phase strands at the second star point 6b are electrically connected to each other. Each strand of a phase can consist of further parallel and / or series-connected subgroups (not shown). The inverter 3rd has three half bridges 4a , 4b and 4c and a capacity 5 which are all connected in parallel to each other. Each half-bridge is designed to generate an AC voltage phase and has two serially connected power switches, in the example as transistors T1 and T2 each with a parallel freewheeling diode D1 respectively. D2 on. The circuit breakers are operated by a control, not shown, for representing a torque on the electric motor 2nd controlled. In the present case, three alternating voltage phases can be generated by the inverter 3rd generated and the electric motor 2nd to be provided. A vehicle battery 7 is with the inverter 3rd connected and supplies it electrically with, for example, 800 volts DC. The inverter can 3rd , especially every half bridge 4a , 4b and 4c , are controlled such that a three-phase alternating current for the electric motor 2nd is produced. The electric motor becomes through the current 2nd set in rotation via the axle drive device 11 a first bike 12a and a second wheel 12b drives. The electric motor 2nd and the inverter 3rd are also designed to serve as step-up converters in a DC charging mode. In particular, the transistors T1 and T2 controlled accordingly. The transistor T1 is blocked and does not conduct while the transistor T2 is opened and closed alternately, so that the corresponding inductance U1 and the freewheeling diode D1 act as a boost converter. Since the groups of stator windings are not electrically connected to a common star point, this has the advantage that no circulating currents can flow between the two stator winding groups while driving. However, only the first group of stator windings can be used in DC charging U1 , V1 and W1 be used, whereby the maximum possible charging current for the vehicle battery 7 is limited. The switching unit 10th has three switches S1 , S2 and S3 and connects a charging socket 9a with the electric motor 2nd (via the switch S2 ), the inverter 3rd (via the switch S3 ) and the vehicle battery 7 (via the switch S1 and S3 for positive and negative pole of the battery). The charging socket 9a is with a charging plug 9b a charging source or charging station 8th electrically connectable as a direct current source. Here are the switches S1 and S2 with the positive pole of the charging source 8th and the switch S3 with the negative pole of the charging source 8th connectable. Is not a charging source 8th on the drive system 1 all switches are connected S1 , S2 and S3 open. Has the charging source 8th the same voltage, e.g. 800 V, as the vehicle battery 7 , the switches S1 and S3 closed and the switch S2 opened to bridge the step-up converter and the charging source 8th and the vehicle battery 7 connect directly to each other. Has the charging source 8th a lower voltage, e.g. 400 V, compared to the vehicle battery 7 , eg 800 V, the switches S2 and S3 closed and the switch S1 opened to the boost converter between the charging source 8th and the vehicle battery 7 to switch.

2nd shows a schematic representation of a second drive system 1a with a loading device according to the invention. Compared to the first drive system 1 out 1 the electric motor differs 2a with a star switch PLC is additionally equipped. This star point switch PLC allows the two star points 6a and 6b to connect to each other electrically. The switch is in driving mode and in generator mode of the electric motor PLC opened and the star points 6a and 6b are electrically separated from each other. With the switch open PLC no circulating currents can flow while driving and thus losses can be reduced. In charging mode, by interconnecting or not interconnecting the star points 6a and 6b the loading can optionally take place via one or more groups or stator winding groups. All star points are preferably connected in a first charging phase, which allows a high charging current and thus a high charging power. In a second charging phase, if, for example, the vehicle battery 7 is almost fully charged, the star points 6a and 6b due to the open switch PLC separated from each other and the vehicle battery 7 is only loaded via one or the first group. This loading phase can be followed by a third loading phase, such as 3rd shown, connect.

3rd shows a further schematic representation of the second drive system according to 2nd , with the vehicle battery 7 only over one phase or half bridge 4a , in particular only over a phase strand U1 a group that is loaded. In the drive converter 3rd is therefore only a converter phase or half bridge 4a in operation. In particular, this makes it possible to adapt the charge dissipation power. In addition, the interconnection of the star points 6a and 6b by means of the switch PLC depending on the permissible charging current of the battery 7 can be chosen to reduce losses.

4th shows a schematic representation of a third drive system 1b with a loading device according to the invention. Compared to first drive system 1 out 1 the electric motor differs 2 B that has no parallel groups or sub-groups of stator windings. There is only one group with three stator windings U , V and W , each on one side with a star point 6 and on an opposite side with a half bridge 4a , 4b respectively. 4c are electrically connected. This reduces the wiring effort with the other components of the drive system 1b ; in particular is just a star point 6 lead out of the stator or a stator housing.

5a shows a schematic representation of a three-phase wave winding of a stator according to the invention 14 to illustrate the term wave winding. The actual arrangement within the individual phase strands within the grooves is chosen arbitrarily. The stator 14 or the stator core is rolled up and shows in an active stator side 21 a variety of stator teeth 15 and stator slots 16 , which are arranged side by side and alternately. The three shaft windings are in the stator slots U , V and W formed that are identical to each other and each around a stator groove 16 are offset from the other two windings. Every wave winding U , V and W has several rod ladders 17th in the active stator side 21 on, each individually in a stator slot 16 are arranged. In addition, the rod ladder 17th in pairs with interconnection bars 18th , alternately in the end of the winding head A 20th and winding head side B 22 , connected to a conductor strand or phase strand. The wave windings U , V and W are at one end with a star point 6 connected and connectable to an AC phase at the other end.

5b shows a schematic representation of a phase phase of a wave winding, the stator and correspondingly the stator axis X circled several times, in the example twice. The representation can be seen approximately as a top view of an end face of the stator. The drawing is to be mentally supplemented by a laminated core with grooves through which the phase strand runs. The rod conductors are in the axial direction 17th indicated by black dots. The rod conductors are through end connectors 18th , which close the half-coils of the wave winding, connected to one another. One end of the phase string can be interpreted as a phase connection, the other end as a neutral point connection. In principle, more than two circulations are also conceivable, in particular 4 or 6.

6a and 6b show a side view and a cross-sectional view of a stator core 19th a stator 14 with two rod guides inserted as examples 17a and 17b . The rod ladder 17a and 17b are one above the other in a stator slot 16 or between two stator teeth 15 arranged precisely or positively. As a result, they form a two-layer system. For connecting to connecting bars (not shown) on the end of the winding head A and B are the rod ladder 17a and 17b longer than the laminated core 19th and protrude on both edges of the laminated core 19th out.

7 shows a segment conductor / rod conductor designed as a stranded wire 17th . Formed strands are wire strands pressed in (rectangular or groove) form, the individual wires being insulated from one another here. The rod conductors can be inserted in stator slots. They can be complemented to form a winding or conductor strand using connecting bars / end connectors.

8th shows a preferred circuit diagram of a three-phase wave winding of a stator, without parallel groups / subgroups. The stator has an active stator part 21 - This is the part of the stator in which the magnetic field formed by the winding has a torque-generating effect; it is also referred to as the active length, and the two winding end sides A 20th and B 22 educated. The active stator part 21 is by a stator sheet metal plate with stator teeth arranged side by side and alternating 15 and stator slots 16 and conductor strands located therein 17th . The stator has three stator windings or phase strands U , V and W on that in the end winding side B 22 be powered at one end and to a star point at the other end 6 are interconnected. There are two ladders 17a and 17b per groove 16 introduced, which is why it is a 2-layer system. The windings have slot jumps, for example in the form of interconnection bars / end connectors 18th in the end of the winding head A 20th and B 22 on; ie a half loop of a winding does not run through two immediately adjacent slots, but rather, for example, a first slot and one 15 . Groove so the 2nd . to 14 . Grooves through an interconnection bridge 18th in the end of the winding head A 20th to be skipped. The connection bars in the end of the winding head B 22 however, skip a smaller number of grooves; such an interconnection bridge connects the rod conductors in a first groove and an example 11 . Groove and skip the 2nd . to 10th . Grooves. These jumps are referred to as stator slot jumps and can occur on both ends of the winding head 20th and 22 be the same size. In this case, the stator slot jump is on the end of the winding end A 20th larger than the stator slot jump on the end of the winding end B 22 . In other embodiments, this can be reversed.

Reference list

1

Electric drive system

1a

Electric drive system

1b

Electric drive system

2nd

Electric motor (also electric drive or traction motor)

2a

Electric motor 2nd with interconnectable star points

2 B

Electric motor with only one group of three phase strands

3rd

Inverters / drive inverters

4a

First half bridge (for the 1 . Phase)

4b

Second half bridge (for the 2nd . Phase)

4c

Third half bridge (for the 3rd . Phase)

5

Capacitance (connected in parallel to the half-bridges)

6

Neutral point

6a

Star point of the 1 . group

6b

Star point of the 2nd . group

7

Vehicle battery (with e.g. 800V DC)

8th

Charging source (also charging station with e.g. 400V DC)

9a

Charging socket

9b

Charging plug (the charging source 8th )

10th

Charging switch / switching unit

11

Final drive device

12a

First wheel with axle

12b

Second wheel with axle

13

Housing (of the drive system)

14

stator

15

Stator tooth

16

Stator groove

17th

Staff ladder

17a

First conductor

17b

Second conductor

18th

End connector / connecting bridge

19th

Stator laminated core

20th

A-side winding head

21

active stator side

22

B-side winding head

A

Cross section through stranded wire conductor

B

Cross section through stranded wire conductor

S1

First switch (the switching unit 10th )

S2

Second switch (the switching unit 10th )

S3

Third switch (the switching unit 10th )

PLC

Neutral switch

T1

First transistor (a half bridge)

T2

Second transistor (a half bridge)

D1

First diode (a half bridge)

D2

Second diode (a half bridge)

U

First winding (of the electric motor)

V

Second winding (of the electric motor)

W

Third winding (of the electric motor)

U1

First winding of the 1 . Group (of the electric motor)

V1

Second winding of the 1 . Group (of the electric motor)

W1

Third winding of the 1 . Group (of the electric motor)

U2

First winding of the 2nd . Group (of the electric motor)

V2

Second winding of the 2nd . Group (of the electric motor)

W2

Third winding of the 2nd . Group (of the electric motor)

X

Stator axis or axis of the stator

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• EP 2527186 A2 [0003]

Claims (12)

Stator for an electric traction motor of a motor vehicle, comprising a laminated core and one or more groups of at least three conductor strands for generating a magnetic field, the at least three conductor strands of a group having a star point and each conductor strand being designed as a stator winding for one phase, the laminated core being one Has a plurality of concentrically arranged and spaced-apart stator slots, wherein each conductor strand in the plurality of stator slots is alternately arranged in a predetermined pattern such that a wave winding is formed. Stator after Claim 1 , characterized in that the stator has a plurality of groups of conductor strands and each group has its own star point, a number of star points being electrically connectable to one another. Charging device for charging a battery of a motor vehicle designed with an electric traction motor designed for a drive operation, a generator operation and a DC charging operation, with an inductance, a drive converter which converts the DC voltage of the battery for the electric traction motor during the drive operation of the motor vehicle or in generator operation rectifies an AC voltage for charging the battery, the inductance together with the drive converter for DC charging operation of the battery serving as a step-up converter, the inductance comprising winding parts of a stator winding of the electric traction motor, characterized in that the stator winding is a wave winding. Loading device after Claim 3 , characterized in that the charging device according to an electric traction motor with a stator Claim 1 or 2nd having. Loading device after Claim 3 or 4th , characterized in that exactly one star point is used for DC charging. Loading device according to one of the Claims 3 to 5 , characterized in that exactly one or more phases are used for the DC charging operation, in particular depending on the state of charge of the battery. Loading device according to one of the Claims 3 to 6 , characterized in that the number of phases used is varied during a DC charging process. Loading device according to one of the Claims 3 to 7 , characterized in that the stator winding has exactly one phase per phase. Loading device according to one of the Claims 3 to 8th , characterized in that the stator winding has shaped strands. Loading device according to one of the Claims 3 to 9 , characterized in that the stator winding is formed from bar conductors and connecting bars. Loading device according to one of the Claims 3 to 10th , characterized in that each strand of the stator winding circles the stator by an integral multiple of 360 °. Loading device according to one of the Claims 3 to 11 , characterized in that the stator winding is designed as a two-layer system.

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