DE3423403A1 - Electric asynchronous motor - Google Patents

Abstract

The present invention relates to a modification of a squirrel-cage asynchronous motor in order to match it to the requirements for actuating drives and positioning drives. According to the invention, the asynchronous motor has two stator-rotor sets which operate with contrarotating rotating fields. The rotors of the two stator-rotor sets are coupled to one another. The level of coupling of the first and second stator-rotor sets can be controlled by controlling the load acting on the stator and rotor windings. In consequence, continuous high-torque positioning of the asynchronous motor according to the invention is possible.

Description

Asynchronous electric motor

Description: The present invention relates to an asynchronous motor according to the preambles of the independent claims 1 to 4. In particular, relates the present invention is based on an asynchronous three-phase motor that acts as a positioning drive can be used.

For positioning devices and other technical applications, at who matter, with high speed, high manpower and large DC motors are often used for the accuracy of moving two parts relative to one another used. DC motors are well suited for such tasks because they have a good ability to regulate, but have the disadvantage that they are relatively are expensive, require a complex control loop and have a short service life.

A three-phase motor with a squirrel cage rotor or with Short-circuit rotor used for drive purposes. Such a three-phase motor works as an asynchronous motor and is therefore mainly used in areas where it only matters to have a simple source of power, but it doesn't matter is the speed at which the rotor works. If you want one with a slip use a damaged three-phase motor as a drive for a positioning device, so it is necessary to operate the motor with a variable supply current frequency. An extremely complex, more expensive and usually a powerful frequency converter is required.

A with a has useful properties as a positioning drive Asynchronous rotor equipped three-phase motor only if it is a mechanical one Has brake that the rotor of the asynchronous motor when reaching a desired Angular position of the asynchronous rotor stops. Without such a brake it is enough low torques acting on the shaft of the three-phase motor to control the positioning drive to bring back out of the desired situation. Should such an asynchronous motor be switched in its direction of rotation, the direction of rotation of the stator field must be switched. Such a field switching is known to the person skilled in the art is undesirable because it can only be achieved with high switching capacities. In addition, a three-phase motor designed as an asynchronous motor only has poor low-speed properties, so that an exact setting of a positioning drive with an asynchronous motor is only possible via a gearbox. The combination of a electrical control with a mechanically controlled transmission is however for many use cases too complex.

Good setting results in positioning drives are regular achieved with stepper motors. However, on the one hand, stepper motors have a very high level Price, which often prevents their use, and on the other hand one with industrial Applications limited power of about a 1/2 KW. They also have industrial Stepper motors have the disadvantage that they can only be positioned uncertainly at high speeds.

The present invention is in contrast to this prior art the underlying task of developing an asynchronous three-phase motor so that it can be used as a positioning drive.

This task is carried out with the engines according to the preambles of the claims 1 to 4 each solved by the features of the characterizing part of these claims.

For the sake of completeness, the prior art is described below indicated publications in which motors are already described, which have two stator-rotor sets: GB-PS 20 43 359, US-PS 35 71 693, US-PS 35 39 891, AT-PS 46 682, US-PS 30 17 553, GB-PS 1 270 247, GB-PS 975 102, EP-A-084717, DE-PS 515 130, EP-A-049 106, US-PS 42 27 187, DE-OS 25 56 272, DE-OS 30 20 660, EP-A-037 307.

The present invention is based on the basic concept through two independent winding sets, which are used both on the stator side and on the rotor side or can be arranged on the rotor side to generate opposing fields, and through controllable short circuit in each of these winding sets opposite Winding sets, which in turn are rotor, rotor or stator winding sets can be, or by controlling the load on the last-mentioned winding sets, the direction of rotation or

Direction of displacement and the torque or the tensile force of the motors to control.

The electrical asynchronous motor described in more detail in claim 1 has via two stators, each with a multiple.

have number of stator windings, the electromagnetic rotating fields produce. usually both the first stator and the second stator be equipped with three stator windings each. Each stator has a rotor assigned, which has at least one rotor winding.

The two rotors are mechanically coupled to one another.

If this coupling is carried out in such a way that the rotors move in the same direction rotate, the stator windings are interconnected in such a way that the of them rotate generated rotating fields in the opposite direction. If the mechanical coupling of the first rotor with the second rotor is such that the rotors are opposite rotate with respect to each other, so are the stator windings of the first and second stator interconnected so that the rotating fields generated by them have the same direction of rotation. There is one controllable each on the first rotor winding and one on the second rotor winding Load connected. This does not necessarily have to be understood as a purely ohmic load because it can, as will be explained in more detail below, an electronic load as a load Switches are used that control the rotor windings with a variable duty cycle shorts. Here, the duty cycle is the ratio of the short-circuit time to the Understood idle time of a rotor winding. The asynchronous motor with the features of claim 1 can by varying the at least one first rotor winding first load acting on the at least one second rotor winding acting second load controlled in its direction of rotation and in its torque will. For example, only the first rotor winding is short-circuited while the second rotor winding remains unloaded, the asynchronous motor runs in the direction of rotation, which is given by the rotating field generated by the first stator. Accordingly can the motor from the direction of rotation given by the direction of rotation of the first rotating field be braked by decoupling the first rotor winding from the first load and the second rotor winding is loaded. This acts on the rotor pair torque generated by the second rotating field.

If the first or second load is pulsed to the first or second When the rotor winding is switched on, by varying the pulse width, the pulse frequency with a constant pulse width, by choosing the phase, etc. any, infinitely adjustable Control of the torque of the asynchronous motor can be made. One of those Motor allows changes of direction in the millisecond range with easier and more precise Positioning and good controllability without switching the three-phase supply of the stator windings would be necessary.

According to the invention, the asynchronous motor can also be those listed in claim 2 Have characteristics. Such an asynchronous motor has a first and a second Stator each with at least one stator winding and a first and a second Rotors that are mechanically connected to each other. The rotors each have a plurality of rotor windings. The directions of rotation of the rotating fields are opposite, if the rotors are mechanically coupled in such a way that they rotate in the same direction, and rectified when the rotors due to their mechanical coupling a have opposite directions of rotation to each other. At least one first stator winding is to a first controllable load and at least one second stator winding to a second controllable load connected. It is true that with such a motor it is necessary the mains voltage to excite the rotating fields generated by the rotor windings To feed slip rings, but such a motor has the enormous advantage that the entire control electronics can be arranged in the stator of the motor.

The asynchronous linear motors described in claims 3 and 4 provide a transfer of the engine principle described in claims 1 and 2 the linear motor.

Such linear motors also enable good positioning, a quick change of direction of the rotor movement without switching the three-phase power supply, only require cheap control electronics and have a long service life. In accordance with the rotary induction motors characterized in claims 1 and 2 can also the linear motors according to claims 3 and 4 quickly by pulse trains being controlled. The device is advantageously used for mechanical Coupling the rotors according to claim 5 a shaft.

The development of the invention described in claim 6 Motors has the opposite to a controllable ohmic load. Advantage; to one special To lead high engine efficiency, since the electronic switch ideally no Has forward resistance and thus does not cause any power loss.

Advantageously, the electronic switches according to claim 7 controlled by a control circuit.

The development of the engine described in claim 8 according to claim 1 has the advantage that the first and second loads are arranged outside the rotor can be.

In the development of the motor described in claim 9 according to Claim 1 eliminates the often relatively quickly wearing slip rings between Rotor winding and the control circuit, as the transmission path between the stator and the rotor is designed as an optical path. For example, the control circuit for each load have a light-emitting diode controlled in its brightness, with which a phototransistor rotating with the rotor is controlled, which either itself represents the first or second load or a semiconductor switching element designed for high currents controls.

Claim 10 describes a simple connection of the rotor windings of the motor according to claim 2 with the three-phase power supply.

A preferred development of the rotary motors is claimed 11 described. Based on the information determined by the measuring device about the angular position, the first and second load can be controlled in such a way that compensates for a deviation between the target value and the actual value of the angular position of the rotor will.

Claim 12 relates to a modification of that described in claim 11 Measuring device for the case of a linear motor.

The measuring device is expediently designed according to claim 13, since the digital detection of the position of the rotor or rotor is a simple signal evaluation enables.

An automatic tracking of the position of the carriage resp.

Rotors in the desired target position is with a circuit according to Claim 14 allows. The attitude will preferably be carried out in such a way that at slight deviation of the nominal position from the actual position of the rotor or rotor the winding of the motor part that delivers the desired direction of rotation, only with a small one Load is applied, while in the case of a strong deviation of the target position from the actual position a permanent short-circuit is generated on the corresponding winding in order to achieve a fast, however, to enable soft tracking of the asynchronous motor in the limit area.

Preferred embodiments of the present invention become explained in more detail below with reference to the accompanying drawings. It 1 shows a circuit diagram of a first asynchronous motor, and FIG. 2 shows a Circuit diagram of a second asynchronous motor.

The asynchronous electric motor shown in Fig. 1 has a first Stator 1 and a second stator 5-. The first stator 1 has three first Stator windings 2, 3, 4. The second stator has three second stator windings 6, 7 and 8. A first rotor 9 is assigned to the first stator 1, while the second A second rotor 13 is assigned to the stator 5. The first rotor 9 has three first rotor windings 10, 11, 12. The second rotor 13 has three second ones Rotor windings 14, 15, 16.

The two rotors are in rotary connection via a shaft 17.

On the shaft 17 three slip rings 18 to 20 are arranged, the Establish an electrical connection to the stationary brushes 21 to 23. Every Rotor winding 10 to 12, 14 to 16 of the first and second rotors 9, 13 is over diodes 24, 26, 28, 30, 32 and 34 polarized in the same direction to the first slip ring connected.

Compared to these diodes, reverse polarity diodes connect the Rotor windings 10 to 12 of the first rotor 9 with the second slip ring 19, while in a similar way through reverse-polarized diodes the rectifier windings 14 to 16 of the second rotor 13 are connected to the third slip ring 20. Between the brushes 21, 22 of the first and second slip ring 18, 19 and between the brushes 21, 23 of the first and third slip rings 18, 20 are the collector-emitter paths switched by two switching transistors. These transistors only serve as a Symbols for electronic switching elements that have a short circuit or open circuit between the respective pairs of brushes 21, 22; 21, 23 can generate.

Of course, such electronic switching elements as Thyristors or triacs.

These electrical switching elements 36, 37 form the first and second, respectively Load for the first rotor windings 10 to 12 and second rotor windings 14 to 16. The switching state of the switching elements 36, 37 is determined by pulse-chain signals which are fed to these switching elements from a control circuit 39. An angle measuring device 38 is arranged on the shaft 17 of the motor.

Such an angle measuring device 38 is usually an optoelectronic one Pulse generator running, for example, a certain digital signal combination generated, which darst.ellt the angular position of the shaft 17. That from the angle measuring device 38 generated digital signal representing the angle is fed to the control circuit 39, in turn based on this digital signal and information supplied to it Suitable control signals for the switching elements 36, 37 are generated via the target angular position. Such a control signal can, for example, be a pulse train of pulses with constant Be pulse length, with increasing deviation of the target angular position from the Actual angular position of the rotor an increasing pulse frequency is selected to thus to increase the duty cycle of the control signal with increasing angular deviation. However, it is clear to the person skilled in the art that pulse width modulation can also be used for control the switching elements can be used.

A different embodiment is shown in FIG. Of the Asynchronous motor shown in Fig. 2 has a first stator 1 and a second Stator 5. The first stator 1 has a first stator winding 2. The second stator 5 has a second stator winding 6. A first rotor 9 is assigned to the first stator, which has three first rotor windings 10, 11 and 12. Accordingly, the second stator 5 a rotor 13 assigned to it, which also has three second Rotor windings 14, 15 and 16 has. The two rotors 9, 13 are on a shaft 17 connected to each other. On the shaft 17 there are three slip rings 18, 19 and 20 arranged with brushes 21, 22 and 23 to a three-phase three-phase power supply are connected. The windings of the first and second rotors 9, 13 are such connected to the slip rings 18 to 20 that the rotating fields generated by the rotors have an opposite direction of rotation. In accordance with that relating to Fig. 1 described execution example is on the shaft 17 a Angle measuring device 38 connected, which represents the angular position of the shaft 17 A digital signal is generated which is fed to a control circuit 39. The control circuit 39 controls the on or off switching state of the switching elements 36, 37, which are connected to the first stator winding 2 or to the second stator winding 6 are connected.

Claims (10)

Electric asynchronous motor Patent claims: Electric asynchronous motor - with a first stator with a plurality of first stator windings, - with a first rotor assigned to the first stator with at least one first rotor winding, - with a second stator with a plurality of second stator windings, - with a second rotor assigned to the second stator and having at least one second rotor Rotor winding and - with a device for mechanically coupling the first rotor with detn second rotor, the stator windings electromagnetic rotating fields generate, d u r u c h e k e n n z e i. c h n e t that the directions of rotation the rotating fields are opposite in the case of rotors (9, 13) rotating in the same direction and in the case of rotors rotating in opposite directions, at least one first Rotor winding (10-12) is connected to a first controllable load (36), and that at least one second rotor winding (14-16) to a second controllable load (37) is connected. 2. Asynchronous electric motor - with a first stator with at least a first stator winding, with a first rotor assigned to the first stator with a plurality of first rotor windings, - with a second stator with at least a second stator winding, - with a second stator associated with the second Rotor with a plurality of second rotor windings and - with a device for mechanically coupling the first rotor to the second rotor, d a d u r c h it is noted that the first rotor windings (10-12) have a first The rotating field produces a second rotating field in the second rotor windings (14-16) produce that the directions of rotation of the rotating fields when rotating in the same direction Rotors (9, 13) opposite and the same for rotors rotating in opposite directions are that at least a first stator winding (2) to a first controllable load (36) is connected, and that at least one second stator winding (6) to a second controllable load (37) is connected. 3. Asynchronous linear motor - with a first stator with a plurality of first stator windings and - with a first associated with the first stator Linear rotor with at least one first laurel winding, d a d u r c h. it is noted that a second stator with a plurality of second stator windings is provided that a second stator assigned, with the first linear runner mechanically connected second linear runner with at least a second rotor winding is provided that the stator windings are electromagnetic Fields produce that the fields are opposite in the longitudinal direction of the linear motor running directions of movement that at least one first rotor winding on a first controllable load is connected, and that at least one second rotor winding is connected to a second controllable load. 4. Asynchronous linear motor - with a first stator with at least a first stator winding and - with a first associated with the first stator Linear rotor with a plurality of first rotor windings, d a d u r -c h g e It is not indicated that a second stator with at least one second stator winding it is provided that a second stator associated with the first linear runner mechanically connected second linear armature with a plurality of second armature windings. provided is that the rotor windings generate electromagnetic fields that the fields opposite directions of movement running in the longitudinal direction of the linear motor have that at least a first stator winding is connected to a first controllable load is, and that at least a second stator winding to a second controllable load connected. 5. Motor according to claim 1 or 2, d a d u r c h g e -k e n n z e i c h n e t that the device for mechanical coupling has a common shaft (17) of the first and second rotors (9, 13). 6. Motor according to one of claims 1 to 5, d a -d u r c h g e k e It should be noted that the first and second loads (36, 37) act as electronic switches are executed, which in their closed state are connected to them Windings (10 - 12, 14 - 16; 2, 6) short-circuit. 7. Motor according to claim 6, d a d u r c h g e k e n n -z e i c h n e t that one to the electronic switches (36, 37) of the first and second loads connected control circuit (39) is provided. 8. The engine of claim 1, d a d u r c h g e k e n n -z e i c h n e t that the first and second rotor windings (10-12, 14-16) on slip rings (18-20) are connected, and that the first and second loads (36, 37) via brushes (21-23) are electrically connected to the slip rings (18-20). 9. Motor according to claim 1, d a d u r c h g e k e n n -z e i c h n e t that the first and second load each have an optoelectronic switching element (36, 37) is that the switching elements (36, 37) on the rotor windings (10-12, 14-16) are connected and rotate with them, and that these switching elements of a with respect to the stators (1, 5) fixed control circuit (39) is optically controlled will 10. Motor according to claim 2, d a d u r c h g e k e n n -z e i c h n e t that the rotor windings (10-12, 14-16) are connected to slip rings (18-20), which are connected to a three-phase power supply via brushes (21 - 23) switchable are. 11. Motor according to one of claims 1, 2, 5 - 10, d a d u r c h g e it is not indicated that a measuring device (38) is provided, which in the case of of a rotary motor, the angular position of a rotor (9, 13) relative to this rotor assigned stator (1, 5) measures. 12. Motor according to one of claims 3, 4, 6 and 7, d a d u r c h g e k e n n n n e i c h n e t that a measuring device is provided, which in the case of a linear motor measures the position of the rotor in relation to the stator. -13. Motor according to claim 11 or 12, d u r c h g e n n z e i c h n e t that the measuring device (38) has an incremental encoder, and that the measuring. device the output pulses of the incremental encoder to one the position the digital signal representing the rotor (9, 13) or the rotor. 14. Motor according to one of claims 11 to 13, d a -d u r c h g e k It is noted that the measuring device (38) is connected to the control circuit (39) is connected, and that the control circuit the ratios of the switch-on times at the switch-off times of the pulse-shaped activated ones that form the first and second loads Switching elements depending on the deviation of the measured actual position of the rotor or the rotor adjusts its target position.