DE277493C - - Google Patents

Description

IMPERIAL

PATENT OFFICE.

PATENT LETTERING

- JVr 277493 CLASS 21 d. GROUP

Patented in the German Empire on October 19, 1912.

If a single-phase series motor according to FIG. 1 is driven mechanically against its direction of motor rotation, it can work as a generator and generate alternating currents of the number of mains periods. According to "Elektrotechnik und Maschinenbau" (Vienna) 1911, Issue 52/53, however, usable energy return to the network is possible without special aids, because resistors r of such a size are switched to suppress direct current self-excitation between the motor and the network according to FIG must that all of the energy supplied by the series motor working as a generator in this

^J 5 is consumed.

If the field winding f. And the working windings c and r of Fig. 3 are connected in series by means of a series transformer t with a transformation ratio λ, the behavior of the machine is characterized by the following two equations:

i. Voltage equation of the excitation circuit f: d I ₁

= h ^r i + dt

■ e _t —e _f ..., (1)

2. Stress equation of the working group c and r:

ο = ί, r, e _t

35

All sizes are instantaneous values, eu = terminal voltage. I ₁ is the current, Y ₁ the ohmic resistance, L _Sl the self-induction coefficient (scatter) of the excitation circuit, t any time, et the voltage on the transformer, 6f the field winding f. I ₂ , r ₂ and L _s ., are the corresponding variables of the working group, e _{r is} the voltage on the rotor r. As a solution to this system of equations, the current i in the excitation circuit (mains current) results in the following form:

i _x = [a sin wt + b cos wt] -f- e ~~ ir ' [C ₁ sin w't + C ₂ cos a>' t] a = kje _r + J ₁ If + ^ j ... . (3a) • (3)

Claims (3)

kv kz are machine constants, w and ω 'angular frequency, a, b, C1, C2 are constants, S r = ri + »V Af is the magnetic conductivity of the transformer flux. The first part of expression 3 is an alternating current with the network period number υ = u »: 2 π, the second part a free, self-excited alternating current with a period number v '= u /: 2 π that is independent of the network. If regenerative braking is to be possible, this free current must be suppressed during braking or generator operation, i. H. disappear with increasing time t. According to equation 3, this applies to positive values of α; with generator operation, d. H. in the case of a negative er, this is only possible if HZr + ^ X-e ,.) (4). Regenerative braking can therefore be achieved as soon as k - ^ - assumes finite values; it becomes more effective, the larger it becomes. Regenerative braking can thus be achieved by interposing the transformer t with low magnetic conductivity or high magnetic resistance. The increase in magnetic reluctance is possible by using high iron inductions or by some other means. For repulsion motors (FIG. 4) (of the Thompson, Deri, Atkinson or Winter-Eichberg-Latour type) there is an expression for the line current iv which corresponds in type to equation 3; but a = k [e, - + I1Σ r + k'2 - rz is the resistance in the rotor circle, Z.Sl the self-induction coefficient (scatter) of the stator circle, A2 the magnetic conductivity of the transverse field Φ2: see also the article cited earlier . From this expression for α it follows that the suppression of self-excitation in repulsion motors with stator or armature excitation and thus regenerative braking of this type of motor is made possible: a) by the high magnetic resistance of the motor itself, especially of the transverse field Φ2; b) that the required braking resistor rv (Fig. 4) is expediently connected in the rotor circuit between the otherwise short-circuited brushes and the scatter coefficient LS1 of the primary (stator) circuit is selected as high as possible. This increase in the scatter coefficient can take place by means of inductors or by increasing the scatter of the transformer located between the motor and the network or by increasing the scatter of the stator winding. For the polyphase series commutator motor (FIG. 5), considerations analogous to those for the single-phase motor apply; Regenerative braking is also possible here by switching on a transformer with high magnetic resistance. An example of such a multi-phase braking circuit is shown in FIG. 6. The devices mentioned can also serve exclusively to prevent self-excitation during motor operation. Patent-A ν Proverbs: 1. A device to prevent self-excitation and thus to enable regenerative braking in wide current and speed limits of single and multi-phase AC commutator motors with series characteristics, characterized in that the working circuit is coupled transformer-wise to the excitation circuit connected to the network outside or inside the motor and in this transformer axis of high magnetic resistance is provided, wherein in a known manner by inserting suitable reactances and resistances in the working or excitation circuit or in both the designated effect _{go is} increased. 2. Device according to claim 1 for single and multi-phase series motors, characterized in that the working windings (r -J- c) or (r) to the secondary winding of a series transformer (t) with a high magnetic resistance as shown in FIG 3 or 6 are connected. 3. Device according to claim 1 for repulsion motors of any kind (with stator or armature excitation, with or without phase compensation), characterized in that the braking _{resistance of the motor operating with high magnetic resistance during braking operation in the transverse field Φ 2} (in the transformer axis) in the working circuit between the otherwise short-circuited brushes (connections) and the reactance of the stator circuit (primary circuit) through upstream choke coils or through. Increase in the spread of the transformer connected between the motor and the mains or by increasing the spread of the primary windings, it being possible for the means mentioned to be used individually, in part or all at the same time. 1 sheet of drawings.