DE2024327C3 - Synchronous reluctance motor - Google Patents

Description

The following will never be the cause of the vibrations

_The use of inductives analyzed. the

^ that by one. Pole flowing river calculated

| ^lU duktivili'il wirJ longitudinal field or. Longitudinal inductance; / ..,

,, " _{.. inI)} t. while those from / wich the poles

For a recess) calculate flowing river

I duktivitäl cross-field or cross-directional L ₁₁ ge

s ^ uHerinufallmomeni \ on Drciphasen-Moio- and the critical idle frequency /. in the

Γ fibili'i ^; Don't turn the engine on for the first time. given by the following equations:

0.014 (1 /./ I ² P
L ₁₁ "

L,

_ "Ji

F mkp.

Ilen /.

Here means:
γ

they are to be calibrated with L _Jr „ and L ₁₁₁ ,,, in exceptional cases. Then be -lieri new Fornu ^1, the equations for the Aulkrtriilfiiümoment and critical LeerlautTrequen / in the following manner:

1.014 (1 '/ ") - / ^J
L, ",

V ~ L ₁ J '"-

L _1n

' -Ί

Next it should be assumed that the consecration: of L ₁ and /. "Can be interpreted in such a way that they vary nil the load, as is shown in the following diagram: where L _{ä is} approximately constant between idling and falling out of action, while L ₁₁ is much larger when idling than when falling outside the rim.

= Moment of step out of step in mkp. / ■ '"= critical frequency in Hz. (' · ■ = voltage applied to the motor per phase. / = Frequency of the voltage. Ρ - number of poles.
I = shunt inductance.
I = series inductance.
f = supply or mains frequency * "'correction factor.
, · = Stator resistance per phase, r "= rotor transverse (field Kvidcrstand per phase. Κ ' = a factor that determines the associated inertia and

Second order quantities taken into account. [· = 0.136 = conversion factor from lbs ft in mkp.

In order to achieve a high step out of step moment, L. _q should be small, while the size M - j

should be, since this makes T ₁ ,,, larger, as can be seen from the equation. However, this is the opposite of / to the condition that must be met for a lowering of /. because it is necessary for this. that L, large and the size (l - 'j ^{k! cin} : this therefore contradicts the high step out of step moment sought. - .. ι

With the known reluctance motors, the following problem arises: Should a motor be designed with a torque dimension in which the material is used economically and the motor size is acceptable. this generally results in a critical frequency that is too high for normal operation. Since in the known reluctance motors the amounts of L _d and L _{q are} approximately constant for all loads and frequencies, high torque out of step could only be achieved at the expense of unsatisfactory critical frequencies.

It has now been found that the critical frequency is suppressed by loading the motor: the highest critical frequency (in relation to the load occurs practically when idling on Fs is supposed to be assumed be that unlike the familiar

Expresses ritt- _L change in L _d and L _q with the load (PS) PS

In the following, it is to be examined what consequences "result if L _d and L" vary with the load in the manner shown in the diagram.

(i) When idling, the criteria for a small value of /, exist. because in the equation for /, L _qn , large

and the size (1

are small. On the other hand is

however, the equation for the moment of step out of step. where the idle values for L _d and L _q are used, not applicable, since the idle values of /.j and L _q cannot be used in the outage state. In other words, the following results: Since the engine is not loaded. iU the moment when falling out of step is not only unimportant at this point, but the values of L _d and measured when falling out of step
Not used.

(ii) When falling out of step, there is a large moment of stepping out of step T _pi " da in the equation for 7 ',,,

/. ",," is small and the size M - ^ "I is large. In anaeben

L _q are allowed when idling

mentioned, at and / -.,

logically the

Measured values of L ₁ , _u .. ^ .. _{l (} do not apply to the idling case or even to the full load, if only the values are taken into account when the operator is stepping outside the vehicle).

This therefore fulfills the two requirements

Reluctance motors L _q with regard to the load 65 fulfilled, which previously contradicted each other, so that the motor is varied, while L ₁ , in a sufficiently constant manner, remains stable from idling to full load at the same time. Under idling conditions, /. ,, and also a high stepping moment should be autiitid L _q with Lj ", or L _q " _t , while it can indicate if L _d and L ₁₁ in the manner with

Load will vary as shown in the diagram is. ·

The invention is therefore based on the object to create a synchronous reluctance motor of the specified type, in which with simple constructive Measures at the same time ensure a high level of fall out of step torque and a low critical speed are.

According to the invention, this object is achieved by that the tooth consists of a tooth web with a certain cross-sectional width and one with the recess consists in one plane, widened tooth tip, which extends to the nominal air gap and that the quotient of the width of the tooth tip measured at the nominal air gap and the cross-sectional width of the tooth ridge is greater than or equal to the quotient of the value for the saturation of the core material specified induction and the value of the induction that occurs when the motor is stepped out in the surface of the tooth tip adjoining the air gap can be measured and at the same time smaller than the or equal to the quotient of the value given for the unsaturated state of the core material Induction and the value of induction is. those when the engine is idling in the one adjacent to the air gap The area of the tooth tip can be measured.

The advantages achieved with the invention are particular in that at low load, i.e. at low mechanical damping, the anchor reaction is increased. as the cross-country cross country is essential is reduced. while with a load on the engine in the range of its /. d. H. with a high mechanical damping, the armature reaction is reduced. there in this case the cross resistance is significantly increased.

Furthermore, the critical speed of the engine can be so far hcrabgedrückl that even by a Voltage drops to the limit where the Mo! Or falls out of step when idling, no instability is caused even when there is approximately zero inertia at idle. What with respect to the critical speed is the worst case. In addition, it causes a reduced transverse resistance increased stability and greater synchronization capability in the area of the molar flow of the motor. It should be noted that the size of the critical speed is proportional to the square root of the cross-field resistance isl. Finally is also at the reluctance motor according to the invention a lower drive current required.

The invention is illustrated below with the aid of exemplary embodiments with reference to FIG Drawings explained in more detail.

It shows:

Fig. 1 is a cross-sectional view of an embodiment of a synchronous reactance motor. of two river bars per pole and three saturable cross-sections per pole, with bridges between the teeth.

2 is a cross-sectional view of a modified embodiment of a synchronous reactance motor rotor. one river barricrc per pole and two has saturable cross-section teeth per pole, bridge links being provided between the poles.

Fig. 3 is a graph showing the relationship of voltage / frequency ratio to frequency of a typical 2 hp Vicrpol synchronous reluctance motor and

Fig. 4 is a graph showing the relationship of voltage frequency to frequency a synchronous reluctance motor according to the invention. The engines shown in the drawing are Quadrupole molors. However, the invention can also be applied to machines other than four-pole machines. Farther are according to Figures 1 and 2 three or two radial, saturable teeth per pole and two or one Flux barrier per pole shown. However, it can also

ίο a different number of radial, saturable teeth as well as flux barriers per pole. Furthermore, there is no need for any river barriers and no teeth as such exist as long as the intended flow path is of such size and characteristic has that it is unsaturated when idling and substantially saturated when stepping out is.

A conventional asynchronous stator is used as the stator 6. The designated 7 runner can from a A plurality of stamped lamellar plates 8 be composed. Each lamellar plate can have one or more Have flux barriers9 per pole, which are in the middle lie above each cross-field axis (Λ ',). The structure or the configuration and the position of the flow barriers9 are selected in such a way that they Increase the moment of exit.

A multiplicity of recesses 11 arranged over the circumference with a backland 11, for example transverse field slots, are there in the area of the outer circumferential surface of the runner? intended. The recesses 11 are arranged symmetrically with respect to the transverse field axis c \ ' _q. Each pair of adjacent recesses II defines between them saturable teeth 12 and säuigbaren bridge members 13.
The saturable teeth 12 and if provided

The bridge members 13 are designed in such a way that, when the load changes, the inductances L _q and L _d vary in such a way that the magnitude of L _{q increases} in the direction of idling, while L _d remains essentially constant. The measured when idling /. "Is in a typical case three times as large as that measured when falling out of step /.". This is achieved in that the saturable teeth 12 and, if provided, the bridge members 13 are dimensioned so that they are unsaturated when idling, are increasingly saturated when the engine is loaded, and are finally completely saturated when the engine is out of action With regard to the bridge elements 13: however, if they are present in the rotor, the size must be taken into account in the same way as that of the teeth 12 when determining the size and properties of the flow path.

This is essential for the engine according to the invention! Criterion, namely that the saturable teeth are empty run unsaturated and are completely saturated when stepping out in the toilet express the following condition:

B,

In the following, this condition is always referred to as "inequality (5)".

20th

Here, more than one saturable tooth per pole is assumed, whereby the individual sizes mean:

fi, the actual saturation density of the steel; B _{m is} the unsaturated flux density level of the steel; (ß, ₄ - B _dir ) _{po is} the flux density in the nominal air gap above the saturable tooth which is adjacent to the saturable central tooth (or the g-axis); (# d4) ni is the flux density measured while idling or calculated for idling in the nominal air gap above the saturable tooth which is adjacent to the saturable central tooth (or the i / axis).

The flux densities (ß, ₄ - B _M ) _pa and (ß _d4 ) "can be expressed by the following equations:

(U _qA -u _M ) _po -

B _g (ma \) \ L _d / smjr /; _v 2 / Λ cos π / \

Here means:

ß ,, (max) = maximum air gap flux density,
p _s = individual position of the saturable

Tooth,

L _d . L _q = inductance values when idling,
/ i, = a characteristic function that

is largely determined by the barrier configuration. The size of Ζ ,, is in the range of 0.6 for typical Motors with any number of poles.

The cross-sectional width I along the saturable tooth and the radius / \, which together define the outer tooth width ir, = 2 r + l , are determined by inequality (5), in which the ratio 2 r / l must be less than that for the Idle condition specified in (5) and must be greater than the condition given for falling out of step in (5).

The stability of the motor according to the invention can be compared in a suitable manner with the stability of a conventional synchronous reactance motor. For a typical known synchronous reluctance motor, the ratio of voltage to frequency is plotted against frequency in FIG. 3. The engine is unstable in the entire area under the curve. As can be seen from Fig. 3, if the frequency is decreased while the voltage / frequency ratio is kept constant at the nominal ratio, the motor first becomes unstable at 36 Hz. Remains unstable up to 20 H / down and then becomes stable again.

In Fig. 4 is a diagram of the voltage * Frequency ratio over the frequency of a synchronous reluctance motor shown according to the invention; this graph shows no instability. The engine is extremely stable, as it can even sink the voltage to the limit where it falls out of step at idle, albeit not causing instability an approximate zero inertia is used at idle, which is the worst case.

An essential, saturable by the introduction

The additional effect caused by teeth is the reduction in the magnitude of the cross-field _resistance r lq during lightly loaded conditions and the tendency of r _2q . to become equal to the longitudinal field resistance r _ld .

The reason for this will be explained below. It is initially assumed that there are none saturable teeth 12 there; the flow in the area of the recesses essentially consists of a highly scattered flux near the pole edges and weak flux lines in the recess area.

The spatial distribution of the induced current over the recess area follows the flow course just described. In other words, the current flow is concentrated in a narrow zone near the pole edges. Thus, the resistance of the recess area can be simulated by a very narrow area of conductive material which is present in the vicinity of the pole edges; it follows that the resistance is great. The total resistance r-, _q of which the resistance of the recess area forms only a part, is therefore large.

If there are now saturable teeth, the flow through each tooth completely surrounds each recess 11, so that the current flows almost uniformly into each recess area. As a result of this, the resistance of all recesses is optimally formed by the entire area of all recesses instead of a very narrow area lying in the area of the pole edges.
Furthermore, a reduced rotor resistance r _{lq causes} a higher stability and a greater synchronization ability. The effect on stability is_considerable, since / _r proportional to | / ·· ,,, and [ r _{2ll is} only a fraction of the conventional \ / r _2q , as it would be without the saturable

Teeth results.

In addition to the effect on motor stability, the saturable teeth affect other characteristics of the motor in the same way. In particular, the starting current is reduced and the synchronization capability increased. The increase in Synchionisierungsfähigkeit results from the Vcrringung of _{/: '(.}

For this purpose 2 sheets of drawings

Claims (5)

Patent claims: 1. Synchronous reluctance motor with a rotor having a cylindrical core made of magnetic material with at least one longitudinal field axis connecting opposite rotor poles. in the direction of which there is a low resistance for the magnetic FIuB. and at least one cross-field axis. at its opposite ends a recess extending transversely to this and enlarging the nominal air gap between rotor and stator is provided and in the area of which flow barriers are arranged radially inside the recesses. that in the direction of the Querfeldachsc there is a higher resistance to the magnetic flux, with at least one tooth extending radially outwardly being present in each recess. characterized in that the tooth (12) consists of a tooth crown with a certain cross-sectional width (/) and a widened tooth head lying in one plane with the recess (U), which extends up to the nominal air gap and that the quotient of the am Nominal air gap, measured width (11x, = 2 r-rt) of the tooth tip and the cross-sectional width (. ') Of the tooth web greater than or equal to the quotient of the value of the induction specified for saturation of the core material and the value of the induction that fall when stepping out of the motor can be measured in the surface of the tooth tip adjoining the air gap and at the same time is less than or equal to the quotient of the value of the induction given for the unsaturated state of the core material and the value of the induction. which can be measured when the motor is idling in the surface of the tooth tip adjacent to the air gap. 2. Synchronous reluctance motor according to claim 1, characterized in that each tooth tip Pilzkopfarti «is developed. 3. Synchronous reluctance motor according to claim 1, characterized in that the tooth tip in Bridge members (13) made of core material. which separate the recess (11) from the nominal air gap. 4. Synchronous reluctance motor according to one of claims 1 to 3, characterized in that three teeth (12) are provided in each recess, two of which are arranged symmetrically to the tooth lying _{on the transverse field axis (.V 11).} 5. Synchronous reluctance motor according to one of claims I to 3, characterized in that in each recess two teeth (12) are provided, which are arranged symmetrically to the transverse field axis (A ',,) are. 60 The invention relates to a Synchroneluklan / motor with a rotor having a cylindrical core is magnetic material at least one opposite pole of the rotor Longitudinal field axis. in the direction of which a finger resistance for the magnetic flux before-hiden is. and at least one cross-field axis at their opposite ends, one across each: running, the nominal air gap / between rotor and stator enlarging recess is provided in the area of which flow barriers are arranged radially inside the recesses in such a way that in Rieh tunu the cross-field axis a higher resistance l'iii the "magnetic flux is present." Except for at least one tooth extending radially outward. Em such motoi is described in U.S. Patent 3,2105S4. Synchronous reluctance motors became the ruin of a simple, effective machine with constant Speed developed that requires a minimum of ar control. The stator of such a motor is similar that of an induction or asynchronous motor The runner vicivlungs are usually injection molded. There are no brushes. Slip rings etc .. to the rotor requires no Gleichstromerrcgung well as with a conventional synchronous motor Thurs. The rotor laminations of known motors of this type have Pclvorsprünge and flow barriers separated by recesses. as is known, for example, for the rotor laminations according to U.S. Patents 2,733,362 and 2,769,108. These arrangements create little contradiction for the magnetic flux exiting one pole through the rotor and then an adjacent pole and greater resistance for the flux flowing between the poles or through the flux barriers and recesses, thereby increasing the motor stall torque . The aforementioned synchronous reluctance motor from US Pat. No. 3,210,584 shows, as is the case with conventional reluctance motors, the tendency to vibrate when lower frequencies are applied. At a frequency of about 100 Hz. The speed of such a motor is "perfectly uniform; however, if the applied frequency is lowered, the rotor can vibrate »observe! will. This means that an oscillation frequency of a few Hz is superimposed on the basic rotor speed. If the motor is operated over a frequency range with its nominal flux level or nominal ratio of voltage to frequency (K / Hz), then the frequency at which the motor starts to oscillate for the first time becomes the critical frequency /,. designated. Are the applied frequencies higher than / _c . so the engine is stable. At J, the motor becomes unstable at first, and at frequencies below /, the motor remains unstable, although it becomes stable again at very low frequencies. Should the product made by these motors be uniform, as is the case, for example, with the manufacture of synthetic fibers. where uniform size is important. so mul; ensure that these vibrations of a Re luctance motor are prevented. For this purpose, the motor operation can be limited to frequencies, the size: as / ,. are, or extensive corrective measures are taken to prevent J ₁ . to shift to values outside the range. It is by no means uncommon for reluctance motors to vibrate at applied frequencies on the order of 40 to 50 Hi. In many cases it can therefore only be ensured with difficulty that the reluctance motors do not oscillate in the intended operating frequency range, which in some applications / wiper is 10 to "! () Hz