WO1998059410A1

WO1998059410A1 - Electrodynamic machine, especially a synchronous alternator and/or motor

Info

Publication number: WO1998059410A1
Application number: PCT/EP1998/003845
Authority: WO
Inventors: Frank Eckert
Original assignee: Frank Eckert
Priority date: 1997-06-24
Filing date: 1998-06-23
Publication date: 1998-12-30
Also published as: DE19880792D2; AU8540798A

Abstract

The invention relates to an electrodynamic machine, especially a synchronous generator and/or motor, comprising rotor and stator coil pairs, each having any number of pole pairs. Said rotor and stator coil pairs are aligned in relation to each other and are situated along the machine axle. The rotors have electrically and mechanically connected rotating field coils which generate fields rotating in the opposite direction to the rotor. When the machine is operating as a motor, the stator coils of the coil pairs are each subjected to an alternating voltage of varying frequency and a free torque is introduced to the connected rotors or the rotor axle in dependence on the difference frequency. When the machine is operating as a generator, an outer torque acts upon the connected rotors or the rotor axle in the direction of rotation and produces a measurable voltage in a non-externally excited part of the stator. The frequency of said voltage depends on the rotary speed of the rotor, the number of pole pairs of both rotor parts, the stator parts and the excitation frequency.

Description

Electrodynamic machine, namely synchronous generator and / or motor

description

The invention relates to an electrodynamic machine, namely a synchronous generator and / or motor with mutually aligned rotor and stator winding pairs of any number of pole pairs, which are arranged along the machine axis, the electrically and mechanically connected rotors having rotating field windings which rotate in opposite directions with respect to the rotor Create fields.

From the European patent application EP 0 311 717 AI a synchronous generator is known which has two spaced stators. The stators enclose two rotors, which are spaced on an axis and have electrical windings.

The windings of the runners are cross-connected electrically. The stator windings are connected in parallel and are subjected to a constant frequency.

However, when the known synchronous generator is operated at a constant frequency or respectively the same field frequency in the windings or stators, this leads to unsatisfactory operation with extremely poor efficiency. Ultimately, there are disturbing harmonics, which are also disadvantageous for the application of the synchronous generator. A proposed separation on the frequency side when the stator windings are subjected to alternating voltage is only used for adjustment by mutual rotation of the

Windings of the stators in the event of an undesirable phase shift.

Based on the briefly outlined known prior art, it is therefore an object of the invention to provide an electrodynamic

Develop machine of the generic type so that it can be used both as a synchronous generator and / or motor or as an alternator, an inexpensive mechanical and electrical construction is to be specified, which also ensures high efficiency in all modes.

The object of the invention is achieved with an object according to the features of patent claim 1, the subclaims being at least useful configurations and

Training includes.

The basic idea of the invention is now to start from a machine which has mutually aligned rotor and stator winding pairs which are arranged along a common machine axis. The rotors have electrically and mechanically connected rotating field windings, which are able to generate fields rotating in opposite directions by a conductive connection or corresponding wiring that reverses the rotating field.

According to the invention, during motor operation of the machine, the stator windings of the pairs of windings are each energized with an alternating voltage of different frequency, a free, tapped torque being established on the connected rotors or the rotor axis depending on the difference frequency.

When operating the machine as a generator, an external torque acts in the direction of rotation on the connected rotors or the Machine rotor axis, which in a non-externally excited part of the stator generates a voltage that can be tapped at a frequency that results from the rotor speed, the excitation frequency of the exciting stator or stator and the respective number of poles.

In a preferred embodiment of the invention there is the possibility of combined operation as a synchronous generator and motor of the electrical machine such that e.g. an internal combustion engine is started by the machine rotating at variable frequencies applied to the stator windings by the induced voltages and currents in the rotor. As soon as the internal combustion engine reaches its operating speed, a torque can act on the rotor via the mechanical connection between the output side of the internal combustion engine and the machine axis, in which case the machine acts as a generator and feeds into the network or generates electrical energy . By increasing or decreasing the variable frequencies, assuming constant engine torque, which is not a condition, however, a change in the generator speed and thereby a power control can be achieved.

According to a further basic idea of the invention, the

Stator of a first of the winding pairs can be supplied with a DC voltage. In this case, an external torque acts on the connected rotors or the machine or rotor axis in such a way that an induced alternating voltage is established on the stator of a second one of the winding pairs, so that the function of an alternator results.

By temporarily shorting the windings of a stator, the machine can be forced to start in asynchronous mode. The mechanical action of a minimum speed or a minimum torque that is otherwise necessary for the operation of a synchronous machine can therefore be dispensed with. In a preferred embodiment, the runners according to the invention arranged on the common machine axis each consist of at least three rod conductors which form a cage rotor.

The rod conductors are short-circuited at the outer end and connected to the ends facing each other in a manner that reverses the field of rotation.

The rod conductors of the rotor of a first of the winding pairs are preferably formed in a connecting section essentially parallel to the cage of the conductor conductors of the rotor of a second of the winding pairs and there are angularly displaced relative to one another in such a way that corresponding rod conductor ends with simultaneous electrical insulation of non-corresponding sections by means of simple Bridges or the like can be connected. To operate the electrical machine as a motor, the stator windings can be operated both with a constant and variable frequency and also with two frequencies that are variable in each case, whereby the principle of the invention is that different factors are used to obtain a corresponding torque or to set a desired speed Field frequencies are required.

For the purposes of the invention, the stator windings always have different field frequencies with respect to one another with the same number of pole pairs and with different mechanical speeds and also different generated frequencies.

In order to obtain a constant output frequency in generator operation, the stator excitation field is changed accordingly with a variable rotor frequency, or with a constant excitation frequency, the frequency in the second stator winding changes with the rotor speed. Motor and generator functions of the electrodynamic machine are distinguished by the fact that in both cases different magnetic field frequencies can be recorded on the respective stator windings and the rotor rotates depending on the resulting difference frequency. In the alternator operating case, as stated, the windings of a stator part are supplied with a DC voltage. This induces a resultant in the windings of the corresponding rotor part upon mechanical rotation

Tension. This creates a rotating magnetic field over the other rotor part, which induces an alternating voltage in the associated stator. A correspondingly higher output can be obtained by increasing the frequency.

The manufacturing costs of the electrodynamic machine can be considerably reduced by the proposed design of squirrel-cage rotors, whereby the rotor parts can be prefabricated cast or injection-molded parts that are mechanically and electrically connected accordingly. The number of rod conductors in each cage runner must be ≥ 3. As the number of rods increases, the waveform of the induced frequency can be changed in the direction of a sinusoidal shape.

The invention will be explained in more detail below on the basis of the description of exemplary embodiments with the aid of figures.

Here show:

1 is a sectional view of the basic mechanical structure of the electrodynamic machine with coaxially aligned rotor and stator winding pairs,

2a, b, c a basic representation of the mechanical (2a) and electrical (2b) interconnection of the rotor and the resulting frequency relationships (Fig. 2c),

3a, b the electrical connection of the stand at

Operation as an electrodynamic alternator and a representation of the resulting frequency components, as well 4a, b and c a side view of the rotor parts of the

Machine and a view of the connection area of the squirrel-cage rotor and a developed representation of the rotor bars of the squirrel-cage rotor with the corresponding electrical connections (FIG. 4c).

The electrical machine shown with the aid of FIG. 1, which can be operated as a synchronous generator and / or motor, comprises a rotor or machine axis 1, which is rotatably mounted in a housing 2. Stator windings 1 * and 2 * are arranged on the housing. The stator windings 1 * and 2 * are spaced apart along the axis 1, the stator windings 1 * and 2 * with associated rotor windings 3 * and 4 * each forming a rotor-stator winding pair.

When appropriately loaded, the stator windings generate e.g. in its formation as three-phase windings with three-phase current, a radially aligned magnetic field. The structure of the windings corresponds to that of known electrical machines. All types of windings, combinations and arrangements are possible in which two magnetic fields or rotating fields arranged axially to one another can be generated. The number of poles and pole pairs is basically arbitrary. The windings can be connected in star or delta.

In addition, when the machine functions as an alternator, the stator winding 1 * can be designed as a simple winding instead of a rotating field winding, since in this case the stator winding 1 * in question is supplied with direct voltage.

The rotor windings 3 * and 4 * are electrically connected to one another in such a way that the rotating field winding of the rotor 3 * in the other rotating field winding, i.e. that of the rotor 4 * causes a rotating magnetic field in the opposite direction.

As shown in principle in FIG. 2a, instead of the rotor windings, rotor bars that have a squirrel-cage rotor can also be used form, be used. The rotor bars provided with the reference symbol 3 in FIG. 2a are connected, as shown by the broken lines, in such a way that the desired reversal of the rotating field results. The rotor bars 3 are electrically short-circuited at their axial ends.

With regard to the electrical connection of the rotor windings, reference is made to FIG. 2b, which also shows the frequency components present or resulting. In this regard, reference is made in particular to FIG. 2c. In this case, f2 denotes the speed of the rotor or machine axis 1. Accordingly, if a three-phase current with the frequency fl flows in a stator winding and the rotor rotates with the frequency f2, a rotating field with the frequency f3 = fl-f2 is induced in the corresponding rotor winding.

This rotating field generates an opposite rotating field with the frequency f4 = -f3 in the other rotor winding. The rotating field in this rotor winding induces in the corresponding stator, i.e. a field with the frequency f5 = f2 + f4 in the respective stator winding. From this follows f5 = f2 - (fl - f2) = 2 x f2 - fl, i.e. the voltage induced in the corresponding part of the stator winding has twice the frequency of the rotor speed minus the frequency of the voltage applied to the first rotating field for a pair of poles.

If the rotor rotates against the direction of rotation of the field from the first stator winding, the frequency of the field of the second stator winding increases by twice the rotor speed of the first field of the first stator winding. The voltage in the second rotating field increases accordingly and mechanical energy is converted into electrical energy.

If two different frequencies are applied to the stator windings 1 * and 2 *, then the rotor axis 1 rotates with the corresponding rotor windings 3 * and 4 * synchronously with the above-mentioned relationship changed to f2. To start, the rotor or machine axis 1 must be accelerated to a corresponding initial speed, as is usual with synchronous motors. In a particular embodiment, by the short circuit of one of the stator windings the machine is in an asynchronous mode and therefore forced to start. Alternatively, there is the possibility of starting up the synchronous motor by changing the differential frequency from zero to a predetermined value. The electrical circuitry of the machine should preferably be designed so that the voltages induced in the rotor largely cancel each other at a standstill, so that no appreciable currents flow in the rotor without a torque acting on the rotor.

The operation of the motor or generator with a DC voltage on one of the stator windings is shown with regard to the connection with FIG. 3a and the resulting frequency components with FIG. 3b.

The moment the frequency of the rotating field of the first stator winding is zero, i.e. a DC voltage is applied, a rotating field or an AC voltage with twice the frequency of the rotor speed is induced in the second stator winding. The level of tension is also dependent on the rotor speed.

When the electrodynamic machine functions as a motor, voltages with different frequencies are accordingly applied to the stator windings, so that the rotor rotates synchronously with half the sum of the two stator frequencies. With a frequency fl = 50 Hz and a frequency f5 = 30 Hz, the speed of the rotor with one pole pair on both stator sides (fl + f5) / 2 = 40 Hz. With a frequency fl = 50 Hz and a frequency f5 = -50 Hz is the rotor speed (fl + f5) / 2 0 Hz. A rotor speed of 25 Hz is given if the frequency fl = 50 Hz and the frequency f5 = 0 Hz.

In the generator function of the electrodynamic machine, a voltage is induced in the second stator winding when the rotor is rotating and a stator rotating field is present, the frequency of which is dependent on the rotor speed. At a stator frequency of fl = -10 Hz and a speed of 50 Hz, ie f2 = 50 Hz, the frequency of the induced voltage is 2 x f2 - fl = 110 Hz. At a frequency of the stator field of fl = 0 Hz and a speed of f2 = 25 Hz the frequency of the induced voltage is 50 Hz.

The mechanical structure and the electrical connection of the rotor windings will be described in more detail with reference to FIGS. 4a to c.

4a shows two squirrel-cage rotors 5 which are formed at a distance from the rotor axis 1 and comprise a stable conductor 4.

The rod conductors 4 of the squirrel-cage rotors 5 are electrically connected to one another at their free axial ends, i.e. short-circuited. In a connecting section, corresponding parts of the bar ladder 4 of the respective cage runner 5 extend into one another essentially parallel to the rotor axis 1, the individual bar ladder 4 of the respective cage runner 5 thus being angularly displaced relative to one another in the direction of rotation, i.e. are twisted that an electrical connection is given by simple bridges 7 (Fig. 4b). This constructive arrangement enables both insulation problems to be solved and particularly simple connections to be designed.

Regarding FIG. 4b, it should be noted that the different diameters of the respective squirrel-cage rotors 5 were chosen only for reasons of clarity in the drawing.

The electrical connection can be realized in that the rod conductors 4 of both squirrel-cage rotors 5 run parallel to one another at a predetermined distance from the longitudinal axis 1 of the rotor via the connecting section 6, and bridges in the form of arcs (not shown) are arranged isolated from the bars across them are, which in turn can be electrically connected to the conductor bars 4 at the corresponding points by conductive webs. The electrical connection of the rod conductor 4 of the cage rotor 5 can be traced on the basis of the development according to FIG. 4c.

The rod conductor or the squirrel-cage rotor can be inexpensively installed in the connecting section 6 by means of prefabricated mechanically and electrically acting contact parts which can be produced as cast or injection-molded parts.

The electrodynamic machine described with the exemplary embodiment, in its operating mode as a motor, achieves high torques even in the range of low speeds. The control power is lower than the drive or generator power for both motor and generator functions. The machine can be used, for example, as a servo motor, synchronous drive and on the generator side in a brushless alternator for motor vehicles and as a frequency converter. At this point it should be noted once again that the stator windings can be designed to be both multi-phase and single-phase, the rotor windings being designed as squirrel-cage rotors, which are preferably electrically connected between the corresponding sections of the mutually facing squirrel-cage rotors in such a way that a rotating field in the winding of the one squirrel-cage rotor produces an oppositely rotating rotating field in the winding of the opposite squirrel-cage rotor.

Reference list

1 Lauferach.se/Machine axis

2 housings

1 *, 2 * stator winding

3 *, 4 * rotor winding

3 runner bars

4 rod ladders

5 squirrel cages

6 connecting section

7 bridges

Claims

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Hj P Φ Cb s; sS tr P Φ Cb tr. φ μ- IQ 0 01 Φ P P rt Φ P P 0 Cb P =

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Φ rt φ N P tr PT t * P HS N P LQ φ 0 iQ - P φ Φ CQ tr N Ω tr LQ HS P Φ

01 HJ p φ g CQ Φ P sS φ g rt HS P rt H- ¹ P Ω Φ Φ tr g μ- CQ g

Ω μ- μ- μ- φ P HS P μ- μ- μ- • Φ sS Cb HS rt N tr φ rt μ- Φ Φ P TJ g μ- tr φ Cb Ω co P Φ P Ω Ω 01 T Cb μ - Φ Φ μ- - • hi Ω Ω φ P μ- 03 tr Φ tr Ω CO tQ 01 P pr tr Ω 0 φ PP Φ Φ P φ μ- tr Q tr PP rt Ω o H, P tr TJ LQ P tr g φ Ω tr μ- LQ μ- Φ P φ PP HS tr

01 Φ φ φ P Φ ö P φ φ TJ tr <! P rt h- ¹ tr Φ LQ P Ω φ N Φ

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Ω 01 P co g P Φ 01 N Ω Hj μ- d Φ P μ- Hj μ- tr φ P co

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Φ rt φ μ- 01 P P = d P φ Hh μ- g μ- J Ω, Hj Φ Φ Φ

Cb μs. Hj Hi rt *> P Hi P g Φ P φ Ω P μ- φ CQ tr hi μ- μ- rt pr Cb p Cb φ P b Hj P tr P Φ P α μ- μ- μ- Ω

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Φ TJ μ- P Hj TJ H | Cb P Hj P μ- P to φ Φ Cb φ tr

-3 μ- Hj Ω Cb Cb HS 1 HS LQ Hj 0 LA ⁾ PPP et tr HS rt to μ- co C pr Φ 2. C φ Φ Cb Φ P LQ P = ^ Hi Φ ^

Ω Φ Ω Hj P μ- Ω d tr g LQ Φ HS P φ φ sS T rt P

PT H; tr d PP Ω tr PN μ- rt Hj Φ α. & P h- ¹ 0 0 φ Ω

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Φ Hj P f LQ Hj P Φ Φ Φ μ- 03 Ω φ pr Cb HS P: iQ p Q P P <01 Cb Φ μ- 2 tr HS LQ Ω pr HS μ- N Hi φ

P Hj tΛ φ TJ M Φ HS h- ¹ PB tr pr tr NP Φ P Φ P

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01 P P tr Cb φ Hj P rt P <P P Mi sS P O φ Φ g Φ p: Φ Φ 0 φ φ Cb Hj

Cb P P μ- LQ Φ P μ- P P tr Cb Hj

Φ P Φ rt φ P 1 P Φ Φ Ω PP HS N Hj Hj tr 1 Φ Φ

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