DE240750C - - Google Patents

Description

IMPERIAL

PATENT OFFICE.

PATENT LETTERING

- M 240750 CLASS 21 d. GROUP

Series-wound repulsion motor. Patented in the German Empire on January 7, 1909.

The circuit of an alternating current commutator motor shown in FIG. 1, in which s denotes the secondary winding of the main transformer, α denotes the stator working winding, e denotes the excitation winding and r denotes the rotor, is known under the name of a series connection repulsion motor. It is readily understandable that under very specific circumstances, which are primarily correct

ίο Selection of the number of poles, motor voltage, transformation ratio of the windings α and r is what ensures the most perfect spark suppression. A precise investigation gives the expression for the ratio of spark voltage, ie the difference between the EMF of the movement and the EMF of the rest, to the EMF of the rest at a previous moment

= φ - \ - α (ψ U ² - ι

(ι)

Here, e means spark voltage at any load condition, e _r EMF of ₂ _ rest at normal moment, φ ratio of the excitation fluxes at the respective torque and at normal torque,

φ = - = - 7 u Ratio of the respective rotational

number of motor at normal speed, U

^{u =} w .- ■

The "normal" torque and the "normal" speed are the torque and the speed to understand which either occur most frequently in the company or the mean value represent.

The quantities α and b are determined by the following equations

b = there)

(Ib)

where p is the number of pole pairs, ν the number of periods in the second, f the winding factor, U ₀ the normal speed in the second, Φ _ο the normal exciter nut (through the entire armature circumference, regardless of the sign), P the total voltage of the motor in cgs units (in Fig. 1 the voltage between points α and β), z _% the number of in series

switched armature conductor, η = - the ratio-

Z ₂

nis of the series-connected conductors of the stator working winding (a in Fig. 1) to the number of armature conductors connected in series.

The course of the spark voltage in the entire operating range of the motor is completely determined by the quantities α and b for a given magnetization curve and can be designed more or less favorably by appropriate selection of these quantities. An important finding now lies in the fact that one can for any number of periods, for any normal speed, for any

Number of poles, for any excitation flux and for any armature winding, the values a and b can always be determined in such a way that the most favorable possible conditions for spark suppression are obtained. The quantity α can take on any desired value by choosing the number of stator turns and b by choosing the total voltage P. So there is the greatest possible leeway in the construction and all other constructive quantities, number of poles, speed, etc. can only be selected from a mechanical point of view. You can let the motor run at any number of times the synchronous speed, just like with the series motor, yes, if it were desired, also at any low undersynchronous speed.
The subject of this invention is the choice of such values for the quantities α and b that the most favorable conditions for spark suppression result. In order to arrive at the determination of the most favorable values of α and b, one must also note that in general the requirement is made that the spark voltage should be as zero as possible at normal speed and normal torque. In this case one obtains

.0 = I - + ■ α (τ - b) , (1 c)

thus a relationship between α and b, so that after elimination of a equation (1) changes into

β φ U * ¹ - b ¹ U

V ^{= 9+} · ⁽²⁾

Now it's just a matter of b one

to insert such a value that for the

e _r

°

entire work area is as small as possible. Strictly speaking, this of course depends on the entire operating mode of the engine, but limits can easily be set for the value δ.

₄ _, within which a favorable spark suppression must take place for all practical cases.

In Fig. 2, the ordinates represent the values

for normal torque at variable speed for different values of δ. b = ο corresponds to the repulsion motor, b = 00 corresponds to the series motor with constant transverse field (ETZ 1907, p. 827), which up to now had the most perfect spark suppression. It can now be seen from the curves in FIG. 2 that for values 1.5 < b <4 the conditions for spark suppression are much more favorable than for the series-wound motor with a constant transverse field, and not only at a speed that is above normal , but preferably also for sub-normal speeds, as a look at FIG. 2 shows. · Changing the circuit of the motor for sub-normal speeds should therefore be avoided. One can always find a suitable value for b that results in favorable commutation conditions for speeds which are below normal as well as for speeds above. To fully assess the spark suppression, of course, the entire operating range must be taken into account, the most favorable value for b being around 2.5 to 3.

It is not at all necessary that the

Choose a value for α exactly equal to -7.

On the contrary, as a detailed investigation shows, it will often be expedient to choose it a little smaller, down to about half, in order to achieve the most favorable proportions. It is only essential that b remains within the limits ϊ, '5 < b <4, and that the entire operating range is covered with the same circuit.

Claims (1)

Patent claim: Series-wound repulsion motor, which covers the whole practically possible operating range without changing the circuit, characterized in that the total voltage of the motor (P), the normal speed (U ₀ ), the total excitation flow on the armature circumference (Φ _ο ) and the number of the armature wires connected in series (z ₂ ) are chosen so that J / 2P - Ϊ / _Ο % .Φ _Ο
has the value 1.5 to 4. 1 sheet of drawings.