DE1413996B2 - ELECTROMOTORIC DRIVE SYSTEM WITH SEVERAL MECHANICAL COUPLED SLEEVE RING MOTORS - Google Patents

Description

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The invention relates to an electromotive drive system with several mechanical coupled slip-ring motors, their torques by resistance adjustment in the rotor circuit are adjustable.

Such a drive system is known (Austrian magazine "Elin-Zeitschrift" VI [1954], Pp. 135 to 140). With this drive system, both motors are operated in the same direction and each over a fluid resistance is continuously set in the rotor circuit.

Electric motor drives, for example for hoists such as cranes, winches, elevators, excavators or even machine tools or other work machines are often carried out with asynchronous motors, there these motors are relatively cheap and robust. But they have compared to DC motors the disadvantage that they are less easy to regulate in terms of their speed or torque. Practically this disadvantage is overcome in that by stepping resistors, preferably in the rotor circuit, the motor torque was adapted to the operating conditions is, the reversal of the direction of rotation of the motor by interchanging two stator phases z. B. with the help of switches or Transductors takes place.

It is already known to change the speed or the torque in slip-ring motors by changing the rotor current. So you leave the latter, for example work on a variable resistor via a rectifier (French magazine »Electricite«, November 1951, pp. 265 to 267).

An arrangement is also already known in which the rotor current via electronic Switching elements (tubes) flows and its constant change by changing the ignition timing Switching elements is influenced (Austrian patent 204 139).

Furthermore, arrangements have already been described that the effective resistance of a Change ohmic resistance in a current path by adding a controllable resistance to the resistance electronic element is connected in parallel. By changing the times in which the controllable Element is live, in relation to the times in which the current flows through the resistor, a certain effective value of the current can be set (M. G. Tschelikin, Elektromotorische Drives, Berlin, 1957, pp. 114 to 118).

It is also known for two motors coupled via a common shaft to be opposed to one another acting, continuously adjustable torques to operate continuously without switching the To be able to pass through the zero point (German utility model 1 796 777).

The invention is based on the object of providing an electric drive with asynchronous motors create, which should be adjustable as far as possible in torque and speed, without that torque surges occur in certain operating ranges and without that in these ranges mechanical switches with fault-prone contacts must be confirmed.

Based on the electromotive drive system, this task becomes the one mentioned at the beginning Kind, achieved in that at least one of the motors in certain torque-speed ranges a torque opposite to the others develops and that the rotor at least of a motor via a rectifier works on a fixed resistance that periodically increases parallel-connected semiconductor valve that can be ignited and erased at any time can be short-circuited.

The electromotive drive system according to the invention is the requirements of a fast, Stepless regulation with contactless components while maintaining the advantages of the application of a robust asynchronous motor offers, to a high degree.

One of the motors is constantly switched in such a way that it develops a negative torque, so that if the speed is reversed frequently - for example by interchanging the Three-phase connections - needs to be reversed, but that it is sufficient only the To adjust the torques of the two motors working inversely against each other. In particular you can use the single motors or min-

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at least one of these motors with a constant mains frequency /, i.e. at standstill the load is provided on the electronic control device, which winds that of the rotor from M, ohmic, the motor M. to be adjusted continuously. Such a torque. If one superimposes the negative rotary-electronically operating control device, at the moment that is shown in FIG. 2 can be realized by the curve M _J2 , for example, in that it is indicated that the positive torque range in the rotor of the asynchronous motor is a rectifier of the motor M ₁ , so one obtains the control range which is arranged via a throttle on a fixed resistance F i g. 3, which works in the vicinity of the zero point, enclosing four quadrants parallel to the fixed resistor. With such a controllable semiconductor element is arranged, the io arrangement, for example, the empty hook can short-circuit the fixed resistor during more or less long periods of time of a crane solely through electronic setting and therefore practically the resistance value of R in a steady manner on the fixed resistor in its effect can be moved up and down without the previously made motor continuously adjustable. applied reversing by swapping the

However, this simple arrangement only covers a 15 stator phase would be necessary.

certain setting range, which is achieved by means of a step-shaped design of the rotor circle

Changeovers in the stator circuit, e.g. B. Star triangle from M ₀ can also be other torque curves

switching, can be expanded, namely as M ₁₁ .-, in F i g. 2, for example a

that the steps and the continuous setting range run as shown in FIG. 4 is shown. In this case

chosen that - depending on the area of application - 20 results in the entire range of positive speeds η

the tap changer to be operated as seldom as possible without operating the tap changer a large positive

to need. tives and still a considerable negative

On the basis of a drawing are schematic torque. One can also use the rotor of M ₀

Embodiments of the invention apply parallel resonance in the following or also in known

described in more detail. 25 ways show a parallel connection of ohmic and

F i g. 1 and 5 electromotive drive systems inductive resistances. By not having two mechanically coupled switching devices that are drawn against each other, one can also check the working slip-ring motors, which would be in the rotor circuit of M., and the resistance R

F i g. 2, 3, 4 and 6 the operating behavior of the connections in the rotor circuit can be switched over _{in steps from M 1}

drive systems according to FIGS. Do 1 and 5 on the basis of 30, but choose the levels so that only

Speed-torque diagrams. seldom level changes are required that

M ₁ and M ₂ are in FIG. 1 two asynchronous so essentially the settings by the

motors that work on a common shaft 1. Regulator Re via the controllable semiconductor element 3

th, with this shaft a work machine A to take place.

drives. The asynchronous motors M ₁ and M ₂ are 35 The switching mechanisms S ₁ and 5, can for example contain a star-triangle changeover _{via switching devices S 1} and S ₂ , phase power network RST of the frequency / fed. Make the rotor swap, provided that the motors of the asynchronous motor M _{1 are} also operated in the same direction, or rectifier 2, on a throttle Dr and a fixed resistor - also switching positions to introduce a tie R. Parallel to the fixed resistor R is a 40 Power braking. The division of the entire motor-controllable semiconductor element 3, which can be switched from reg power to, for example, two separate motors ler Re, both in the conductive and in the blocked state, although this brings a somewhat increased price and space-saving state; the latter incurs a lot of effort, but on the other hand, according to the invention, for example, by means of capacitor current surges on the negative side, it provides a wide range of polarity possibilities. 45 to relieve the current in the rotor and also in the

In Fig. 2 is shown in the speed-torque diagram stator of asynchronous motors usual stepped pattern by the hatching, which areas with ter. As a result, the service life of these switches of this simple electronic setting arrangement is increased many times over; In addition, the operation of only the motor M _{1 can be} mastered. In order to achieve the negative hatched 50, order depending on the area of application must be such that it is precisely in the area in which a reversal of the rotating field, i.e. a step switch, would have to switch very often, the corresponding electrical actuation of the switching mechanism S ₂ , he - Niche control device becomes effective, which is still required. In some applications it is advantageous that the latter works continuously and not in steps, without step switching or reversing.

of the rotating field, the four quadrants in the vicinity of the zero point. After that will generally be sufficient. The invention can make this possible by the fact that the second one _{develops the ratio of the division depending on the AnMotor M 2,} a negative torque, select different turning area, for example, in the case mentioned it only needs about 20 ° / o the negative torque is only given in the vicinity of the main motor power, so that in the zero point in the speed-torque diagram it essentially only shows the friction losses of the drive. Such a torque can be able to overcome. On the other hand, it can also be achieved, for example, by adding the largest rotor of the motor M ₂ to the non-electronically adjustable motor with a rotor shown in FIG. 1 transferred part of the power and provides the electronically Neten resonance circuit CLr and make this 65 adjustable motor just as large as circuit at resonance with the mains frequency / but depending on the operating conditions to avoid it. In this case, the rotor frequency of the frequent actuation of the step switch required is the _{same as the motor M 2} when the shaft 1 is at a standstill. Under certain circumstances you can use the two engines

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unite constructively into a unit. The two The arrangement according to the invention can with VorMotoren different numbers of pole pairs can also be used to drive machine tools to have. For example, the smaller motor with which the direction of rotation can be changed frequently a higher synchronous speed must be used.

the, so that z. B. in cranes the empty hook with 5 As in F i g. 1 is shown, the control

double speed raised or lowered tion of the controllable semiconductor element 3 with the

can be. Of course you can both motorcycle actuation of the switching stations S ₁ and S ₂ such auto-

Link the ren automatically with an electronic control device so that simple operation,

see if this corresponds in the given case, for example only the input of a setpoint

relieves the load on the tap changer. io of the torque, the speed or the position

The functions of the tap changer can of course be applied to the working machine, as shown in FIG. 1 indicated, he

there are also anti-parallel controlled semiconductor elements. If you make the two motors M ₁ and M _{2 of} the

or by electronically controlled resistors or F i g. 1 is about the same size, you may have

be met by transducers. But if you still have the advantage that if one of the

According to the invention, depending on the application 15 engine with the other engine an emergency operation

the electronic actuators for the most common can maintain. You can do both

When the control processes are used, motors have different gear ratios

the tap changer so relieved that you can work for them in on the shaft 1, which may be

will use mechanical switches in many cases. Advantages in the dimensioning of the motors or

Of course, during the actuation of the 20, one will bring about the control.

mechanical switches the electronic actuators To a particularly interesting arrangement, set the current strengths as low as possible, so if you use two asynchronous motors of the same size as possible with the switching arcs on the contacts, both of which are electrically small in the rotor. Instead of the fixed resistor R in tronic, key circuit explained above on-F i g. 1 one can under certain circumstances also refer to a 25, as shown in FIG. 5 is shown. In this collector battery, on a voltage-dependent figure, identically labeled parts correspond to resistance or a DC motor working to those in FIG. 1. The switching values are used for switching. In all of the cases mentioned , the rotating fields in ken S ₁ or S would be in opposite directions, so F i g. 2 hatched control range can be expanded, the in F i g. 6 indicated by hatching, however, at most only up to the zero line of the rotary control range, which is symmetrical around the zero torque point of the diagram.

1 sheet of drawings

Claims (5)

Patent claims: 1. Electromotive drive system with several mechanically coupled slip ring motors, the torques of which can be adjusted by adjusting the resistance in the rotor circuit, characterized in that at least one of the motors develops a torque opposite to the other in certain torque speed ranges and that the rotor of at least one motor (M ₁ ) works via a rectifier (2) on a fixed resistor (R) , which can be periodically short-circuited by a semiconductor valve (3) connected in parallel, which can be ignited and removed at any time. 2. Drive system according to claim 1, characterized in that in addition to the continuous setting brought about by the semiconductor valve (3), a change in the setting range in steps by electronic or mechanical switches (S ₁ , S ₂ ) is provided in the stator circuit. 3. Drive system according to claim 2, characterized in that the settings that occur frequently are made by the continuously acting on-actuators (3), and those that occur rarely by the on-load _{tap changer (S 1} , S.,). 4. Drive system according to one of claims 1 to 3, characterized in that the fixed resistor (R) is dimensioned such that in the vicinity of the zero point of the torque-speed characteristic field all four quadrants can be reached only by actuating the continuously acting adjusting members. 5. Drive system according to one of claims 1 to 4 with two identical motors, characterized in that that also the rotor of the second motor via a rectifier to a fixed one Resistance works, which is periodically switched by a parallel, ignitable and extinguishable at any time Semiconductor valve can be short-circuited (Fig. 5).