Engines:

Engines single-phase currents with induction: General information
These engines single-phase currents are composed of a stator carrying a winding with p pairs of poles and of a squirrel-cage rotor in shortcircuit. With the stop the rotor is requested by two spinning field patterns in opposite direction. This engine thus does not start spontaneously. While launching the rotor (with the hand for example) it can then start indifferently in a direction or the other. One adds the second shifted winding of 90° in the remaining notches: the launching phase or auxiliary phase fed through an artifice of dephasing, capacitor, resistance, or inductance. Two engine torques due to the two spinning field patterns appear then: the couple of the field which turns in the same direction that the rotor is largest and tends to increase with speed. The second couple, antagonist, are almost null. The field reverses induced a current with 100 Hz in the rotor which produces a vibration, and losses with the rotor, and a noise which can be awkward in certain cases. The engine single-phase current has less of slip than the polyphase motor but it has a worse power-factor. Under too strong load it can take down: with the stop the intensity becomes very strong then and the engine can roast if it is not protected by a circuit breaker.
Engines with induction with capacitors
With permanent capacitor
Two-phase engine
Its winding comprises 2 equal phases occupying each one half of the notches, the inversion of the direction is obtained by simple permutation of the feeding at the boundaries of wire going to the permanent capacitor, with other with dimensions a commun run. The powers are equal in the two directions of rotation. Used for the very small powers. Generally used for controls of valves, one "then dopes" his power but for an intermittent service.
engine with permanent capacitor and winding says "1 ⁄ 3 - 2 ⁄ 3".
Its winding includes a principal phase which occupies 2 ⁄ 3 of the notches, and the auxiliary phase occupying the remaining third. The number of whorls of the auxiliary phase is in general the double of that of the principal phase, its section being half of that of the phase of functioning. The phase of functioning is located U1-U2, auxiliary phase Z1-Z2. The inversion of direction being done by crossing of connections of a phase compared to the other - by crossing Z1-Z2 or U1-U2 (*). The auxiliary phase being in circuit permanently, in series with a capacitor says "condensing permanent". The capacitor is a model with metallized polypropylene film - car healing, or sometimes with the impregnated oil paper. Value of the capacity: tens of µF. These engines have weak starting torque : CD ⁄ CN ranging between 0,3 - 0,8 *. They is traditional low end engines of large surface what one does not say to you). One must thus hold his use with uses where one can tolerate a weak starting torque: centrifugal pumps, machines starting with vacuum, etc
Diagram with permanent capacitor.
Operation:
The capacitor produces dephasing necessary to the feeding of the auxiliary phase, the two circuits ]principal phase_ - ]auxiliary phase + condensing_ remain fed permanently.
Characteristics:
(table sheets catalogs manufacturers, to come)
the location of wire, capital, is sometimes made by wire of various colors or numbers, in this case the only recourse will be to have the diagram of its engine, or then to make use of an ohmmeter and to know what one must find What is sometimes not so obvious, even for the professionals)
Starting capacitor engine (and with winding "1 ⁄ 3 - 2 ⁄ 3")
The winding comprises two "phases": a "phase of functioning" or "principal phase", and a "auxiliary phase" or "launching phase". The winding of the phase of functioning, which occupies two thirds of the notches, its wire is larger, it with lowest ohmic resistance. The "launching phase", which occupies it remains to it notches is the remaining third.
Location of connections at the final boundaries: Phase of functioning: U1-U2, launching Phase: Z1-Z2
The engine comprises also an artifice of starting, which can be: That is to say a contact centrifuges made up of a revolving part interdependent of the tree (in general with dimensions opposite drive and right behind the ventilator); it is about a system with runners deviating abruptly under the effect of the centrifugal force at a certain speed; and of a fixed contact interdependent of the back flask. Maybe of a relay of starting: Klixon relays which are current relays whose contact is closed under the action of the overcurrent of starting and is reopened as soon as the current returned to the face value and that the engine is started Either of a relay of starting Leroy Somer, which is a relay of tension placed at the terminals of the auxiliary winding of phase.
Whole or part of wire are brought back to a plate on terminals of which the provision - concerning the engines single-phase currents - is more function of the "culture" of the various manufacturers than of established standards.
These windings are carried out in notches full occupied by the conductors with only one phase. However the American and unquestionable manufacturers English have habit to carry out diagrams having notches shared by the two phases, or windings called in "half-notches", but sometimes still of windings 3/3 where the two phases share "half-notches" in all or left the notches
Operation :
Starting :
one feeds the phase of functioning, in parallel with the circuit ]relay or contact of starting + condensing + auxiliary phase_. The relay cuts as soon as the engine is launched, then only the phase of functioning remains fed. A current relay (small black case on three Faston terminals, generally of Klixon mark), comprising a reel in series with the "phase of functioning", attracting the pallet of a contact which feeds a short moment the circuit: ]launching phase in series with the capacitor_ to launch the engine. On other models it is a centrifugal switch with runners which cuts the circuit ]launching phase + condensing_ beyond a certain speed. Leroy Somer uses a patent Somer, system with relay of tension supervising the evolution of the terminal voltage of the auxiliary phase it even in series with the capacitor. The new range of single-phase currents of the manufacturer of Angouleme rests besides entirely on this system, engineers asserting LS - endurance tests to the support which it is more enduring that the centrifugal switches.
The capacitor, known as "capacitor starting" is an electrolytique capacitor of strong capacity: hundreds of µF, for Intermittent Service *) These engines have a strong starting torque : CD ⁄ CN ranging between 1,5 to 3 what is quasi equivalent to Cd ⁄ Cn of the three-phase asynchronous motors.
Diagram with current relay and starting capacitor.
(Errata: symbol I should be I in the relay)
This type of capacitor does not support to remain under tension longer than the time of a starting, beyond it can explode.)
Engine with starting capacitor and permanent capacitor
Improvement of the CD ⁄ CN, the speed and power-factor
Engines with induction without capacitor
Engine "Split-Phase" or with high-strength launching phase
It is an old system, still used by the American manufacturers, memory of the time when for lack of a reliable technology of the capacitors, the mono engines started using a resistance, sometimes a coil, in series with launching and the centrifugal switch phase of starting (sometimes a current relay). Here resistance was integrated into winding by the important ohmic value given to the starting winding (great number of whorls, weak section). Sometimes one used even wire of winding out of enamelled iron, it was a trap for the coil winders, if they did not realize any, the engine did not walk more after rewinding very out of copper This system is fragile: the auxiliary phase, very fine, can roast quickly following a blocking or a centrifugal defect of contact. It nevertheless is always used by Anglo-Saxon, American, and Asian manufacturers to produce economic engines and where one does not ask for strong starting torques.
Starting:
The number of whorls of the principal phase is higher than that of the launching phase = the Reactance of the principal phase is higher than that of the launching phase. The Resistance of the launching phase is very high (genuine silver wire) compared to that of the principal phase. Two rollings up are connected in parallel. In the starting winding the current is almost in phase with the tension, while in the principal phase there is a back dephasing in consequence of its Reactance. The flow of a pole being in phase with the current, the flow of the starting winding is in advance on the flow of principal rolling up, that giving rise to a spinning field pattern.
Characteristics:
Cd ⁄ Cn : 1 to 2
Engine with winding starting known as "two-wire", (or with reversed whorls)
Winding is composed of 2 dissymmetrical phases (generally 1 ⁄ 3-2 ⁄ 3): The phase of functioning is wound normally. The launching phase is wound in a particular way: 70¨% of its whorls are wound in a direction, in all the notches reserved for the launching phase, and the 30% of remaining whorls are wound with back in the same notches (except exception on certain small pumps where only the reels of the greatest step comprised whorls opposite). The fact of adding reversed whorls increases only the Resistance of the auxiliary phase, one leads to the same result as with the engine "Split-Phase", in a little more solid. One obtains economic engines having a small starting torque, nevertheless higher than what one would obtain with a permanent capacitor engine.
Operation
As the engines monos with starting capacitor had a terminal of the capacitor connected in contact with a relay or of a centrifugal clutch, the launching phase is connected here directly in contact with a current relay (Klixon, ELD), or to a centrifugal contact which cut it as soon as rated speed is reached
Characteristics:
Diagram with current relay, without capacitor.
symbol I should be I in the relay)
Various alternative of winding of the Phase of Functioning
Certain American engines bitension have their principal phase rolled up with "two wire in hand" which pass by all the reels of the principal phase, that is to say two circuits which one can couple in series or parallel. One carries out the coupling series (high tension) twice by connecting the end of a circuit to the beginning of the other while passing in the reels. For the parallel (low tension) one connects together two wire to the input and the output.
American windings:
Certain manufacturers prefer to carry out windings 3 ⁄ 3: the two phases are numbers of whorls and different sections, winding is on two plans, the principal phase occupying almost the totality of the number of notch, with a sinusoidal distribution of the numbers of whorls (variable).
Engines Bi-tension (110/220 V)
To avoid overloading I chose to show only diagrams with a single voltage motors, but obviously there are dual voltage motors. This is just a serial or parallel coupling of the coils of the phase of operation, the auxiliary phase or boot is provided for 110 V, and connected to one side of the "bridge" in the case of series of use the voltage "high" (serial connection).
Engines multi-speeds with sockets
If one wants to have several speeds (in general two) one can carry out two windings of different polarities. But in the case of the use in distribution, with rotors known as "slipping", one then uses windings with only one polarity, but one "lengthens" the principal phase (addition of whorls) to decrease the power by it, which will cause to make slip the engine with its load (the propeller of the ventilator) and to slow down it. Certain Italian manufacturers go until multiplying the sockets to realize up to 5 or 7 speeds! Two provisions of their diagram being possible: in L or T.
Engines multivitesses with autotransformer with sockets
Used in distribution. It is permanent a capacitor engine supplied with an autotransformer comprising several "sockets" connected to the engine via a switch, the variation of power obtained by reduction of the supply voltage of the engine causes a variation load speed. That returns to same when one does that with an electronic variator of tension.
Different fireworks start
Capacitors of functioning
Starting capacitors
Capacitors permanent
Contactors of starting
Centrifugal switches
Current relays
Relays of tension
Electronic relays
Mono special switch
Timing relays
Thermister PTC of power
capacitors of two technologies are found
with insulation impregnated paper of oil, which is presented in the form of aluminum tubes crimped with a valve of security located beside the Faston thimbles of connection. - with metallized polypropylene film - car healing : most of the time out of white plastic case sealed with the resin, but certain marks still do them under tube crimped aluminum. The usual tensions of insulation are about 400 - 450 V~
Car healing
mean that the design of these capacitors authorizes microcomputer-startings between reinforcements, startings with the repairing effect "car": each time an overpressure or a weakness of the insulation of the capacitor arises, it occurs inside the reel of the capacitor a mini explosion in a zone very localized between two layers of dielectric, which causes to volitilize a negligible part of aluminum of the reinforcement and to restore the function of capacitor at once. These capacitors can thus live several "small deaths" and go some not more badly, where capacitors of other technologies would have returned the core since glosses! But it should be known that with this play the capacitor leaves a little feathers, and that gradually it will miss microfarads, until the day when the engine will pain to start
Starting capacitor
They are capacitors strong values, produced in "electrolytic" technology, for intermittent service. They are presented in the form of a black bakelite or plastic cylinder. They are "electrochemical" capacitors nonpolarized, known as " for starting of engine single-phase current" Their tensions of insulation are of : 110, 160, 220, 260, 330 V~
Permanent " and "capacitor starting capacitors" are bought at the coil winders (at which one will find also the relays of starting), the salesmen of spare parts for large electrical appliance, and also Radiospares, Farnell, etc
The capacities of the capacitors are added by connecting them in parallel.
Most widespread, assembled on the tree with dimensions opposite drive, behind the ventilator. Various models are used according to the manufacturers
Gone up in series with the phase of functioning, operating a fast contact on auxiliary phase. Principle: the relay sticks with the call of current with starting, the contact closes and feeds the auxiliary phase (in series with the capacitor if it there a), but the current decrease abruptly in the principal phase when the engine approaches its normal speed, which causes to open the contact when the threshold value of the relay is reached and to cut off the supply of the launching phase.
Marks: KLIXON, ELD (which are electromagnetic current relays, with contact NO), and ETA (which is a thermal thermal switch relay, with contact NC for which it is thus necessary to reverse the reasoning given above)
Gone up in ⁄⁄ on the auxiliary phase (except capacitor): stuck or not according to the evolution of the terminal voltage of the launching phase. Principle: the terminal voltage of the auxiliary phase believes with the speed of the engine; contact NC of the relay feeds the auxiliary phase during starting, then to a certain tension of threshold, when the speed of the engine is close its normal speed, the relay sticks, cutting off the supply of the launching phase; The tension induced in the auxiliary phase is enough to maintain the relay closed moving, this avoiding an annoying beat.
User: Leroy Somer

Diagram with relay of tension, capacitor.
The body of commutation consists of a triac, and an electronic tempo.
Marks: ABB, LCR, ALMOR
For the "manual" starting of certain grinders, one finds also switches bipolar of which one of the contacts is of "maintained" type. One actuates the lever, one maintains it with the finger the time of starting, then one slackens, then the lever - which is in two parts - brings back the contact maintained to the position "open". It is the latter contact which is used to feed the launching phase in series with the starting capacitor. The other contact remaining in position goes to feed the winding of functioning.
Mark: Marquardt (ABE-AGEMO)
A tempo, electromechanics or electronics, out of traditional or modular equipment, to feed the auxiliary phase via its condo of starting a short moment: 1 to 2 seconds.
It is about a large varistor "with positive temperature coefficient", which one inserts in series with the launching phase, the current which crosses it sweat and increases its resistance abruptly, thus making it "nonbusy" and stopping the circuit of starting. Used in the hermetic groups of certain refrigerators (Danfoss, Maneurop)
Marks: Standard Siemens: J 19 - (a figure moreover for the gauge in amps) TI - Klixon: types SP
Diagram of starting per thermister PTC.
Polyphase motors in single-phase current
With capacitors
One speaks much to make function the polyphase motors in single-phase current. It is possible, if one admits a loss of power of 30%, and a loss of starting torque for the diagrams with 1 only capacitor. To forget only the machines which the private individuals want to transform with few expenses were already motorized generally "with the short-nap cloth of the daisies" by their manufacturers Thus to remove 30% of power to them amounts taking a risk However that goes rather well except for the restrictions, for example: to avoid for the machines asking a strong starting torque (the traditional question concerns combined it machinery woodworking or the compressing good old man * which one believed that it was a business), and still that for little that one puts the price at it out of capacitors and equipment. If the machine has a simple wiring it is playable, if not the best consulting is to buy an engine single-phase current
with starting capacitor
But this type of engine is not with the reduction with the do-it-yourself department, but one will find at the craftsmen and industrial coil winders of the engines of completely accessible Italian marks to the private individual
Because if operation approaches some, there will not be a mono truth, one will have just a machine arranged with a bad output, but the handyman is ready with very to avoid buying mono with strong starting torque to 1500-2000 F! Good: you will have been warned. Several diagrams are possible that one will adapt according to the needs and windings. Indeed, certain diagrams function with certain engines, others not: that is due to their construction, with their diagram of winding.
connection
Principal phase = a phase of the sorting, auxiliary Phase = two phases in series.
Principal phase = two phases of the sorting in series, auxiliary Phase = 1 phase of the sorting
Engine in triangle
Two windings thus distributed thus have thus their shifted respective axes of 90°, a capacitor of suitable value will be used to feed the auxiliary phase. This connection makes it possible to have the maximum of power in 220 V, always by counting a loss of the third of the power of origin.
This connection with two phases in series for the principal phase, although more logic to approach winding 2 ⁄ 3 - 1 ⁄ 3 of truths single-phase currents, should be used with double tension, that is to say in 400 V single-phase current. Or then in 220 V it will be necessary to divide by two the hoped power
Most usually used, can be wrongly: -)
Principal phase = 2 phases of the sorting in parallel, auxiliary Phase = the remaining phase Little used, because functions only under certain conditions of diagrams of winding and with small engines. (small pumps of machine tools, with low number of notches, e.g.)
height of axis
engine
power
sorting (kw)
power
mono (kw)
condenser of
starting µf
condenser
permanent µf
In 220
rated current 220V
In 220
running starting 220V
80 0,55 0,37 120 30 2,2 11,5
80 0,75 0,55 225 32 3,3 18
90 1,1 0,75 300 47 4,2 25
90 1,5 1,1 500 75 6,1 38
100 2,2 1,5 560 90 8,3 45
100 3 2,2 650 140 12,2 60
112 4 3 1100 250 17 90
1 CV = 0,736 kw
Nature of the capacitors
Cd : standard capacitor "starting" (electrochemical for alternate 50hz, mono driving starting) 260/330 V~ (is added, the time of starting, 1 to 2 seconds, in ⁄⁄ on the capacitor of functioning) One can use special switches with double contact of which a "maintained" contact, or a fast marking time ordering a relay of starting capacitor.
CP : standard capacitor "permanent" (polypropylene or paper ⁄ oil) 400 ⁄ 450 V, One can put only ’one permanent capacitor but it should S `be ensured that the engine starts with all the blows.
With a "pilot engine " or transformer-converter of phases, One uses a tri engine which one makes start in neutral in first, with the artifices referred to above, then one can connect another tri engine at the boundaries of this engine holding place of generator: it is the "pilot" engine. Then one can connect other engines if the pilot engine is of suitable size, then the network thus created gradually increases his capacity in starting capacity with the contribution of new loads.
Three-phase converter of mark ISOMATIC (the U.K.)
With a frequency converter, One uses a frequency converter or variator of frequency which starting from the network 230 V single-phase current reconstitutes three shifted phases of 120° electric with a law U ⁄ f: 230V-50 Hz
It is enough to cable the reference speed to have always the maximum and to program F max: 50 Hz, and to ensure themselves that one is well in the case of figure of a law U ⁄ f 230 V - 50 Hz, or simply on certain models to turn the potentiometer at bottom on the right and not to touch more there. Obviously to regulate the slopes of acceleration and deceleration to suitable values, the manufacturers being careful in their presettings by putting rather long slopes If the engine must often start, one leaves the variator under tension and one uses a small switch of starting cabled on the electronic ordering of the variator. If the load is involving or with strong inertia, it is imperatively necessary to use a resistance of braking connected to the good place on the variator (in series with the chopper of braking integrated into the majority of the variators), if not the variator will put at fault "over-voltage" during deceleration.

Asynchronous motor

General information and principle of operation

The asynchronous motor coupled to a variator of frequency is by far the type of engine more used for the applications where it is necessary to control the speed and the displacement of a load.
The system engine-variator is appropriate well for applications such as the lifts because one seeks an excellent precision with time on the level the speed (comfort of the users) and precision of the position of the cabin compared to the bearings.
As for the asynchronous motor only, its popularity results from little maintenance necessary, of its simplicity of construction, its standardisation and its robust.
     

Principle of operation

The principle of operation of an asynchronous motor rests:
On the one hand on the creation of an electric current induced in a conductor placed in a revolving magnetic field. The conductor in question is one of the bars of the squirrel-cage below constituting the rotor of the engine. The induction of the current can be made only if the conductor is in short-circuit (it is the case since the two side rings connect all the bars).
In addition, on the creation of a driving force on the conductor considered (traversed by a current and placed in a magnetic field revolving or variable) whose direction is given by the rule of the three fingers of the right hand.

As shown towards the diagram above, the spinning field pattern, at a given moment, is directed upwards. By considering two conductors diametrically opposed, one notes that the currents induced in these two conductors are in opposite direction and, associated with the magnetic field, create driving forces in opposite direction. The rotor being free to turn on axis X there, the two forces join to print with the two conductors a couple allowing the rotation of the squirrel-cage: the electrical motor is invented.
To maintain rotation the engine, it is necessary to vary either the current in the conductors of the cage, or the magnetic field. In an asynchronous motor, it is the magnetic field which varies in the form of spinning field pattern created in the stator.
With starting the spinning field pattern sweeps the conductors of its flow at the angular velocity of synchronism. The rotor put in rotation tends to catch up with the spinning field pattern. So that there is a couple maintained on the level the conductors, the flux variation must be present permanently; what means that if the conductors turn at the speed of synchronism like the spinning field pattern, the flux variation on the conductors becomes null and the engine torque disappears.
An asynchronous rotor of motor thus turns never at the speed of synchronism (50 Hz). For an engine with a pair of poles (to 50 Hz, the disk speed of the spinning field pattern is of 3000 ]tr ⁄ min_) the disk speed of the rotor can be 2.950 ]tr ⁄ min_ for example; the concept of slip intervenes here.

Slip, couple, disk speed

As one saw on the level of the principle of operation of an asynchronous motor, the disk speed of the tree of the engine is different the speed of synchronism (speed of the spinning field pattern).
The slip represents the difference in disk speed between the tree of the engine and the spinning field pattern of the stator, it is expressed by the following relation :
n0- N
With
n0 = speed of the spinning field pattern.
N = disk speed of the tree.
The slip is generally expressed expressed as a percentage speed of synchronism n0.
S = (n0 - N) ⁄ n0 ]%_
The speed of synchronism, as for it, is function of the frequency of the network and the number of pairs of poles. It is expressed by the following relation:
n0 = (F X 60) ⁄ p
With
n0 = speed of the spinning field pattern.
F = the frequency of the network (in general 50 Hz).
p = the number of pairs of poles.

Couples

The couple C of an asynchronous motor is function of the power P and disk speed N of the engine. It is expressed by the following relation:
C = (P X 9550) ⁄ N
With
P = engine Output ]W_.
N = disk speed of the engine ]tr ⁄ min_.
One of the curves most characteristic of the asynchronous motors is that of the couple according to the slip:
Couples according to the report ⁄ ratio: disk speed ⁄ speed of synchronism.
On the graph above one sees immediately that it is necessary to choose the type of engine according to the application: for the motorizations of the lifts, one will prefer the double squirrel cage motors presenting a flatter profile of curve according to the slip in order to profit from a relatively constant couple whatever the load.
One of the characteristics important of the asynchronous motor, is that it can, under certain conditions, to transform itself into asynchronous generator. When a lift car goes down again in peak load, the engine returns energy to the network.
The following curves show this phenomenon:
Function out of engine or generator following the resistive torque.
To be complete, one can note that a traditional asynchronous motor has the following characteristics:
The inrush current is about 6 to 7 times the rated current. It is imperative to envisage systems of limitation of current to starting (star ⁄ delta, variator of frequency,).
The starting torque is important (about 2,5 times the nominal couple).
The couple is maximum for a slip of about 30%.

Characteristics of a traditional asynchronous motor.

Control disk speed
The control disk speed of the asynchronous motor is essential for many applications.
The following relation makes it possible to encircle which are the parameters which can influence the disk speed.
One a:
S = (n0 - N) ⁄ n0
With
S = slip ]%_.
n0 = speed of the spinning field pattern ]tr ⁄ min_.
N = disk speed of the tree of the engine ]tr ⁄ min_.
Or:
N = ((1 - S) X F) ⁄ p
With
F = frequency of the network ]Hz_.
p = the number of pair of pole.
One can thus control the disk speed while intervening on:
the number of pair of pole (driving two-speed for example)
slip of the engine (driving with ring)
the frequency of the network.
Control by modifying the number of poles
Old installations of lift still function with two-speed engines. Most of the time are engines whose rotor is composed of two numbers different of pairs of poles. Rollings up are laid out in the notches of the stator in a particular way which in fact all its complexity. The various couplings per pair of poles makes it possible to obtain various speeds.
A bipolar engine has a disk speed of 3.000 ]tr ⁄ min_, while quadripolar turns at 1500 ]tr ⁄ min_ or 3000 ]tr ⁄ min_.
Thus in so far as one can carry out different couplings on engines with two numbers different of pairs of poles, one obtains different speeds.
Regulation of frequency
At present, the control the speed of the asynchronous motors is done electronically thanks to variable speed transmissions. For this reason, one will speak here only about the control of the frequency which by far most current.
Lossless of power, one can control the disk speed of the engine while varying the frequency because the disk speed of the spinning field pattern on the level of the stator changes. To preserve the engine torque (interesting for the lifts), it is necessary that the tension of the engine changes with the frequency in a constant report ⁄ ratio. Indeed, the couple is related to the frequency, the tension and the current by the following formula.
One a:
C ~ (U ⁄ f) X I
With
C = engine torque ]Nm_.
U = tension of the network ]V_.
I = running absorbed by the engine.
If the relationship between the tension and the frequency remains constant, the couple the remainder too.
Control in frequency and tension.
The control of the engine by a variator of frequency and tension shows unquestionable interests; with knowknowing mainly:
the limitation of the inrush current (about 1,5 times the rated current);
a cut relatively constant whatever the speed of the engine.

The synchronous motor

General information, principle of operation and characteristic

The synchronous motor is also an engine used for the motorization of the lifts. These last years saw this driving type of return in force parallel to the development of the variable speed transmissions.

Principle of operation

The synchronous motor is composed, like the asynchronous motor, of a stator and a rotor separated by an air-gap. The only difference is at the level of the design of the rotor. The figure below watch a rotor with projecting poles made up of permanent magnets or electromagnets supplied with D.C. current.
After starting, the engine turns in synchronism with the spinning field pattern. With vacuum the axes of the poles of the spinning field pattern and the rotor are confused. In load, the axes are slightly shifted. The speed of the synchronous motor is constant whatever the load. It will be also noted that:
The load (the lift operating system) should not exceed the effort of starting between the rotor and the spinning field pattern.
The engine torque is proportional to the tension on its terminals.

Characteristics

The advantages and disadvantages of the synchronous motor are mentioned below:
(+)
it can work with a power-factor close to 1 (cos φ ~1). It thus contributes to rectify the total φ cos electrical installation.
the speed of the engine is constant whatever the load (interesting in the case of the lifts).
It can support voltage drops important without taking down.
(-)
If it is not associated with a variable speed transmission, it has difficulties in start.
it can take down in the event of strong load (not interesting at the level of the lifts requiring an important couple).

The stator

The stator of a polyphase motor (more running on average and large power), as its name indicates it, is the static part of the synchronous motor. It is connected extremely with the asynchronous stator of the motors. It is composed mainly:
carcass
bearing
deeks of bearing
ventilator cooling the engine
the cap protecting the ventilator.

Stator.
The interior of the stator includes/understands primarily:
a laminated iron core so as to channel the magnetic flux
rollings up (or winding out of copper) of the three phases placed in the notches of the core.
In a polyphase motor rollings up with the minimum number of three are shifted one of the other of 120° as the diagram shows it below.
Variation speed according to the number of pairs of poles.
When rollings up of the stator are traversed by a three-phase current, those produce magnetic fields turning at the speed of synchronism. The speed of synchronism is function of the frequency of the feeder system (50 Hz in Europe) and of the number of pair of poles. Considering the frequency is fixed, the speed of the engine can vary according to the number of pairs of poles.
Pairs of poles 1 2 3 4 6
Many poles 2 4 6 8 12
n0 ]tr ⁄ min_ 3000 1500 1000 750 500

The rotor



The rotor is the moving part of the synchronous motor. Coupled mechanically with a winch of lift for example, it will create a engine torque able to provide a work of rise and descent of the lift car. It is composed primarily of a succession of north poles and South intercalated in the form of permanent magnets or of reels of exitation traversed by a D.C. current. One thus distinguishes two types of engines:
with permanent magnets
with rotor wound.

Permanent magnet rotor

In fact engines can accept important currents of overload to start quickly. Associated with variable speed transmissions electronic, they find their place in certain applications of motorization of lifts when a certain compactness and a fast acceleration are sought (real great height for example).

Wound rotor

This type of machines is reversible because they can work at a driving normal rate as in mode alternator. For the averages and large powers, the wound rotor synchronous motors, associated with a variable speed transmission, are powerful machines.
As shown in the figure below, the rotor is composed of a stacking of ferromagnetic discs. As in the stator of the engine, of rollings up are placed in notches practised on the rotor and are electrically connected to the rings of shaft end. The D.C. current supply is carried out via the ring-brushes unit.

Control disk speed

The control disk speed of the synchronous motor is essential for many applications.
The following relation makes it possible to encircle which are the parameters which can influence the disk speed.
One a : n0 = N
With
n0 = speed of the spinning field pattern ]tr ⁄ min_.
N = disk speed of the tree of the engine ]tr ⁄ min_.
or : N = f ⁄ p
With
F = frequency of the network ]Hz_.
p = the number of pairs of poles of the stator.
One can thus control the disk speed while intervening on:
the number of pairs of poles (engine to variable number of poles)
the frequency of the network.

Regulation of frequency

At present, the control the speed of the synchronous motors is done electronically thanks to variable speed transmissions. For this reason, one will speak here only about the control of the frequency which by far most current. Considering requires for a synchronous motor to be started with an auxiliary system (the rotor cannot "hang" stator spinning field pattern a too fast of 3000 ]tr ⁄ min_), the variator of frequency associated with the synchronous motor allows to start it with a weak stator frequency even null.
Lossless of power, one can control the disk speed of the engine while varying the frequency and the tension because the disk speed of the spinning field pattern on the level of the stator changes.
To notice that the couple of a synchronous motor does not change according to speed since there is no slip.

Variation from speed with constant couple (synchronous motor).

The control of the synchronous motor by a variator of frequency shows unquestionable interests; with knowknowing mainly:
The limitation of the inrush current (about 1,5 times the rated current)
A constant couple whatever the speed of the engine.

The engine with D.C. current

General information, principle of operation and characteristic

One still regularly meets engines with D.C. current with separate excitation in the computer rooms of the buildings of a certain age. In general, they belong to a Ward-Leonard group which makes it possible easily to vary the disk speed.
Currently, of the Ward-Leonard group, one preserves only the engine at D.C. current which, this time, is associated with a static variable speed transmission (electronic variator) whose technology is simpler and not very expensive while requiring little maintenance and by offering performances raised in a range very broad speed (from 1 to 100%).

Principle of operation

The engine with D.C. current is composed:
inductor or stator
armature or rotor
collector and brushes.
When the winding of an inductor of engine is fed by a D.C. current, on the same principle as a permanent magnet engine (like the figure below), it creates a magnetic field (flow of excitation) of North-South direction.
A whorl able to turn on an axis of rotation is placed in the magnetic field. Moreover, the two conductors forming the whorl each one are electrically connected to a collecting half and are fed in D.C. current via two brushes wipers.
According to the law of Laplace (any conductor traversed by a current and placed in a magnetic field is subjected to a force), the conductors of the armature placed on both sides of the axis of the brushes (neutral line) are subjected to equal forces F but direction opposed by creating a engine torque: the armature starts to turn!
If the system brush-collectors were not present (simple whorl fed in D.C. current), the whorl would stop turning in driving position on an axis called commonly "neutral line". The system brush-collectors has as a role to make commutate the direction of the current in the two conductors with the passage of the neutral line. The current being reversed, the driving forces on the conductors are also thus allowing it to continue the rotation of the whorl.
In practise, the whorl is replaced by an armature (rotor) of very complex design on which are assembled the rollings up (compounds of a great number of whorls) connected to a collector "fixed" in shaft end. In this configuration, the armature can be regarded as a single rolling up similar to a single whorl.

Characteristics

The advantages and disadvantages of the engine with D.C. current are mentioned below:
(+)
accompanied by an electronic variable speed transmission, it has a broad range of variation (1 to 100% of the range)
regulation specifies couple
its independence compared to the frequency of the network made of him an engine with broad field of application
(-)
not very robust compared to the asynchronous machine
important investment and expensive maintenance (maintenance of the collector and the brushes

Reversible machine

In the mode of operation of the lifts with traction, the winch with D.C. current can:
Sometimes to function out of engine when the system cabin and counterweight are opposed to the rotation movement (load known as "resistant") the engine takes energy with the network.
Sometimes to work out of generator when the same system tends to support rotation (load known as "involving"); the generator returns energy to the network.

Type of engine with D.C. current

According to the application, windings of the inductor and armature can be connected in a different way. One finds in general:
Engines with separate excitation.
Engines with parallel excitation.
Engines with excitation series.
Engines with made up excitation.
The majority of the machines of lift are configured in parallel or independent excitation. The inversion of the direction of rotation of the engine is obtained while reversing either connected them inductor or armature.

The inductor

The inductor of an engine with D.C. current is the static part of the engine. It is composed mainly:
carcass
bearings
deeks of bearing
gates brushes.

Inductor.
The core even of the engine includes ⁄ understands primarily:
A whole of pairs of poles made up of a ferromagnetic sheet stacking.
Rollings up (or copper winding) intended to create the field or the magnetic fields according to the number of pairs of poles.
For engines of a certain power, the number of pairs of poles is multiplied in order to better use the matter, to decrease dimensions of obstruction and to optimise the penetration of the magnetic flux in the armature.

The armature

The armature of the engine with D.C. current is composed of a tree on which a whole of ferromagnetic discs is piled up. Notches are axially applied to the periphery of the cylinder formed by the piled up discs. In these notches rollings up (reels of the armature) "are wound" according to a very precise and complex diagram which requires a particular manpower (high costs). For this reason, one prefers, in general, to direct oneself towards engines with more robust and simple AC current in their design.

Induced.
Each rolling up is composed of a series of sections, they even made up of whorls; a whorl being an open loop whose outward journey is placed in a notch of the armature and the return in the notch diametrically opposite. So that rolling up is traversed by a current, its return and starting conductors are connected to the commutator segments (cylinder fixed on the tree and composed in periphery of a succession of copper foils spaced by an insulator).
Composition of the armature.
The interface between the feeding with D.C. current and the collector of the armature is provided by the brushes and the brush holders.

Brushes

The brushes ensure the passage of the electric current between the power supply and windings of the armature in the form of a contact by friction. the brushes are out of graphite and constitute, in some kinds, the wearing part. Graphite while wearing releases a dust which returns the engine to D.C. current sensitive to a maintenance correct and thus expensive.
The balas unit, brush holder and collector.
The contact point between the brushes and the collector constitutes the weak point of the engine with D.C. current. Indeed, it is at this place, that in addition to the problem of wear of graphite, commutation (inversion of the direction of the current in rolling up) takes place by creating microcomputer-arcs (sparks) between the plates of the collector; one of the great risks of degradation of the collectors being their setting in short-circuit by wear.

Control disk speed

Relation Speed and counter electromotive force with constant flow
When the armature is supplied under a continuous or rectified tension U, it occurs a counter electromotive force E.
One a : E = U - R X I ]volts_
Where
R = the resistance of the armature ]ohm_.
I = the current in the armature ]amp_.
The counter electromotive force is related at the speed and the energization of the engine.
One a: E = K X ω X φ]volt_
Where
K = constant clean with the engine (depend on the number of conductors of the armature).
ω = angular velocity of the armature ]rad/s_.
φ = the flow of the inductor ]weber_.
By analysing the relation above, one sees, that with constant excitation φ, the counter electromotive force E is proportional to the disk speed.

Relation Couples and flow

As for the engine torque, it is related on inductive flow and the current armature by the following relation.
One has: C = K X φ X I ]N.m_
Where
K = constant clean with the engine (depend on the number of conductors of the armature).
φ = the flow of the inductor ]weber_.
I = the current in the armature ]amp_.
By analysing the relation above, one sees that by reducing flow, the couple decreases.

Variation speed

Within sight of the relations existing between speed, flow and the counter electromotive force, it is possible to vary the speed of the engine in two different ways. One can:
To increase the counter electromotive force E by increasing the tension on the terminal of the armature all while maintaining the flow of the constant inductor. There is an operation called to "constant couple". This type of operation is interesting on the level of the control of lift.
To decrease the flow of the inductor (flow of excitation) by a reduction of the operate current by maintaining the supply voltage of the armature constant. This type of operation imposes a reduction of the couple when speed increases.

The Ward-Leonard group

The Ward-Léonard group represents the old generation of the winches of lift with traction with cables. This system made it possible to vary the speed of an engine with D.C. current with separate excitation by regulating the tension of the armature via a generator with D.C. current which one varied the excitation; the generator being involved mechanically by an engine with traditional AC current.
For a weak variation of the operate current of the generator, it was possible to control enormous powers of engines with D.C. current in a range of variation very wide speed.
The electronics of regulation speed came to supplant the system of the Ward-Léonard group where the electronic variable speed transmission comes to control:
that is to say directly an engine with AC current
that is to say the engine with D.C. current only survivor of the Ward-Léonard group.

Stepper motor

A stepper motor makes it possible to transform an electric impulse into an angular movement. This type of engine is very current in all the devices or one wishes to make speed control or of position in open loop, typically in the systems of positioning. The most known use of the general public is in the printers connected to a computer (positioning of the tète of impression and rotation of the roller toilet-roll fixture in the dot-matrix printers, with daisy and jet of ink, and rotation of the roller toilet-roll fixture only in the printers with xerography with laser).
Three types of stepper motors are found:
the engine with variable reluctance
the permanent magnet engine
the hybrid engine, which is a combination of two preceding technologies.

History

The stepper motor was invented by Marius Lavet in 1936 for clock making industry.

Engine with variable reluctance

The engines with variable reluctance (driving MRV) owe their name with the fact that the magnetic circuit which composes them opposes in a variable way to its penetration by a magnetic field.
These engines are composed of a soft iron bar and a certain number of reels. When a reel is fed, it becomes an electromagnet and the bar of iron naturally seeks to be directed according to the magnetic field. Phase 1 is fed, then phase 2, then phase 3 If one wants to change the direction of the engine, it is enough to change the command of feeding of the reels.
In practise, the ferrite bar has several teeth (here 6). As soon as phase 2 is fed, there is a rotation of 15° (that is to say 60° - 45° = 15°), then phase 3, etc Donc the engine turns of 15° as soon as a phase is fed. One needs 24 impulses to make a full rotation. It is an engine 24 steps.
Disadvantages: require at least three windings, to obtain a complete cycle, not residual couple, that is to say not under tension, the rotor is free, which can be problematic for this kind of engine. Manufacture is rather delicate, the air-gaps must be very weak.
Advantages of the system: not very expensive, of a good precision. In the example, with only 4 rollings up, one obtains 24 steps (one can easily obtain 360 steps). The direction of the current in the reel does not have any importance.

Permanent magnet engine

The permanent magnet engines are similar to the engines with variable reluctance, except that the rotor has north poles and CUS. Because of the permanent magnets, the rotor remains braked with its last position when the power supply ceases providing impulses.
A way simple to see the system, is to place a compass between two magnets. According to the reel which is fed and it direction of the current, the magnet will be aligned with the field.

Bipolar permanent magnet engine

Operation with complete step
not n°1 not n°2 not n°3 not n°4
Summary table about the phases
Impulse Wind has Wind has Wind B Wind B
T1 + -    
T2     + -
T3 - +    
T4     - +

Operation with maximum couple

One feeds the reels, two by two each time. There are always four steps.
not n°1 not n°2 not n°3 not n°4
Feeding of windings
Impulse Wind has Wind has Wind B Wind B
T1 + - + -
T2 + - - +
T3 - + - +
T4 - + + -

Fontionnement with half-not

If two operations are mixed, one can obtain the double of step, to make a full rotation, one needs 8 steps. One speaks then about half-not.
not n°1 not n°2 not n°3 not n°4
not n°5 not n°6 not n°7 not n°8

Unipolar permanent magnet engine

In the preceding examples, one saw that one feeds rollings up in the two directions of current, it exists versions with halfcoils (with a point medium). The advantage is that one never reverses the direction of the current, therefore the command is simpler. All the problem is that one "doubles" the number of rollings up, therefore the engine is more expensive and cumbersome, nevertheless that remains very current for the small powers.
not n°1 not n°2 not n°3 not n°4

Hybrid stepper motor

The hybrid stepper motor borrows engine from permanent magnet and machine with variable reluctance. It is thus with variable reluctance but with a permanent magnet rotor. The advantage is a number of very high step.

Principles common to the stepper motors

Dynamic characteristic
The stepper motors are not the fast engines, fastest seldom exceed the maximum speed of 3000 tr ⁄ min.
This "slowness" helping, and these engines being naturally without brushes (the majority of the stepper motors of high-quality moreover is equipped with rolls of the dice), these engines have one lifespan extrèmement long, without requiring maintenance.

Influence load and kinematics

Any application implying the use of a stepper motor requires to collect the critical informations with a good dimensioning:
mass of the load to be involved (in kg)
its inertia (in kg.m2)
the mechanical type of drive (screw, notched belt, toothed rack, etc)
the type of guidance, in order to estimate frictions (dry and viscous)
efforts of work (in NR)
the most critical displacement (distance according to a time).
The influence of the load is directly related to the calculation of the engine torque via the parameters of inertial calculation (in kg.m2) and of acceleration (in m.s-2). For parameters of acceleration and kinematic chain identical, a stepper motor will not need the same couple according to the concerned load.
For an industrial application, the dimensioning of a stepper motor must be calculated in a rigorous way or to be oversize in order to avoid any problem of slip per "loss of step". The stepper motor functioning in open loop (without control), it does not recover its position of instruction in the event of slip.

Control of the reels

For a bipolar standard stepper motor.
It is the principle of the Bridge out of H, if one orders T1 and T4, then one feeds in a direction, that is to say one feeds in T2 and T3, one changes the direction of the feeding, therefore the direction of the current.
Minicomputer-conclusion: the bipolar engine is simpler to manufacture, but it requires 8 transistors whereas the unipolar engine requires only 4 transistors.
A stepper motor is an inductive load. Like visible above, diodes of free wheel are necessary to ensure the flow of the current during the blocking of the transistors, for example with each request for reduction of the current (regulation by chopper), or with each request for change of direction of the current (change of step).

Engine brushless

An engine without brushes, or driving brushless, is an electric machine of the category of the synchronous motor, whose rotor consists of one or several permanent magnets and is equipped with origin of a rotor position encoder (sensor with Hall effect, synchro-synchro-transmitter, incremental coder for example).

Operation

Seen outside, it functions in D.C. current. Its name (of English Brushless) comes owing to the fact that this type of engine does not contain any turning collector and thus not from brushes. On the other hand an electronic system of command must ensure the commutation of the current in the stator windings. This device can, either be integrated into the engine for the small powers, or outside in the shape of a convertor of power (inverter). The role of sensor the more electronic unit of command is to ensure the car-control of the engine that is to say the orthogonality of the rotor magnetic flux compared to stator flow, role formerly reserved for the brush-collector unit on a machine with D.C. current.

Evolutions compared to the machine with D.C. current

Engine of ventilator without the rotor one sees there the reels (diphasic engine)
Ventilator of dismounted computer
Diagram out of cut of an engine without brushes of low power to external rotor.
This type of electrical motor eliminates all the disadvantages from the engine with traditional D.C. current: problems of commutation on the level of the collector, hoop removing, inertia, cooling (the losses joules being located at the stator they are easier to evacuate), specific power definitely larger, geometry, lifespan in particular the index of protection (IP) can be increased compared to the machines with D.C. current because of absence of brushes.
With equal performances, its output is always better, this being partly with the absence of mechanical and electric losses related to the brushes (especially at the time of weak loads). But also most of the time with its notably reduced inertia compared to a machine equivalent to D.C. current, this parameter being dominating in many applications, in particular in the phases of acceleration.
Always with equal performances, the engine without brushes is of a cost price lower than that of the machine with D.C. current because of the replacement of the collector and the brushes by an electronic sensor of a very reduced cost. For the small powers, this sensor provides the two sampling functions of detection of the rotor position and of the current. In this case, operation identical, is seen outside, with a machine with D.C. current: it is enough to vary the supply voltage to vary the disk speed and in many uses this does not require the recourse to an electronic variator speed (small ventilators for example, sensors with Hall effect incorporated in the stator also ensuring commutation of the phases).
For the large majority of the applications requiring a ordering and an electronic regulation of the couple, speed and ⁄ or position, the advantages of the engine without brushes are such as it completely replaced the machine with D.C. current and, in connexion with progress of the electronics of power (for example IGBT), the cost price of these solutions was tiny room in same time of it that their performances were notably improved.

Uses

Engine of disk drive of computer
The engines brushless are largely used in industry, in particular in the servomechanisms of the machine tools and in robotics, or they made disappear the machines with D.C. current. One finds such engines for couples of a few newton-metres until several hundreds of Nm and the powers of a few hundred Watts until hundreds of kilowatts.
They equip in particular the hard drives and the DVD burners.
A simplified and popular form of these technologies is used in the ventilators ensuring the cooling of the microcomputers. In this case, the stator (wound) is inside and the rotor (comprising the magnets) outside.
In the field of transport, the electrical motors which equip the hybrid vehicles like the Toyota Prius and Honda Civic IMA to ensure, inter alia, operation at low speed are also engines without brushes. Engines of the brushless type are also used for the systems of distribution air-conditioning of cars since the years 1990 one of the main advantages in this case is their silence.
They also equip bicycles with electric assistance, bicycles which one actuates while pedalling as on a traditional bicycle but or an engine comes to help with the effort. Certain scooters present on the market also use this engine for low speeds or in total replacement of the thermal engine.
They also are very much used in model making to make be driven small-scale models of aircraft, helicopters (model aircraft making). They are less noisy than the engines with brushes. However the engines without brushes of radiocontrolled small-scale models are often assembled with the hand, contrary to the traditional engines with brushes and their cost is still higher (2009).

Possibilities of coupling of the engine 2 Dahlander speeds

By the play of parallelization or series, of coupling star or triangle, the various theoretical diagrams below can prove to be useful since they make it possible to convert engines 2 speeds with coupling Dahlander (mono tension), out of engine Bi-tension 1 only speed.

Coupling of the engine 2 Dahlander speeds TRI 220v to transform it into TRI 220/380v low speed.

The diagram of origin is the following
Connections of origin of rollings up are out of chestnut.
Coupling triangle (220)
Coupling star (380):
Connections in yellow represent the coupling triangle or star of the bars on the plate on 6 terminals of the engine. This coupling allow to keep all the characteristics of’ origin, number of revolutions in load and power, the Dahlander coupling at the same speed.

Coupling of the engine 2 Dahlander speeds TRI 220v to transform it into TRI 220/380v high-speed.

The diagram of origin is the following
Connections of origin of rollings up are out of chestnut. The coupling in yellow is that of the bars of the plate on terminals of the engine positioned in coupling star.
Coupling triangle (220)
Coupling star (380)
Modified connections are of green color. Connections in yellow represent the coupling triangle or star of the bars on the plate on 6 terminals of the engine. In this configuration of coupling, the engine output is only to 85% of the power obtained in Dahlander coupling at the same speed.

Coupling of the engine 2 Dahlander speeds TRI 380v to transform it into TRI 220 ⁄ 380v low speed.

The diagram of origin is the following
Connections of origin of rollings up are out of chestnut.
The diagram for the modification is the following
Coupling triangle (220)
Coupling star (380)
Modified connections are of green color. Connections in yellow represent the coupling triangle or star of the bars on the plate on 6 terminals of the engine. In this configuration of coupling, the engine output is of 15% of more than of the power obtained in Dahlander coupling at the same speed. The main drawback it is that few modern engines support the parallelization of rollings up, this being with the saturation of the electrical sheets which generate noise and overheating of the engine.

Coupling of the engine 2 Dahlander speeds TRI 380v to transform it into TRI 220 ⁄ 380v high-speed

The diagram of origin is the following
Connections of origin of rollings up are out of chestnut, the yellow coupling represents the bars of the plate on terminals positioned in coupling star.
The diagram for the modification is the following
Coupling triangle (220)
Coupling star (380)
Modified connections are of green color. Connections in yellow represent the coupling triangle or star of the bars on the plate on 6 terminals of the engine. This coupling allow to keep all the characteristics of origin, number of revolutions in load and power, the Dahlander coupling at the same speed.
chart helps you determine the power of the motor according the height of the motor shaft.
Power to KW Frame in
size mm
Diameter of
spindle poles
Axis length
in mm
Diameter of
shaft mm 4-6-8 poles
Axis length
in mm
0,55 - 0,75 80 19 40 19 40
1,1 - 1,5 90 24 50 24 50
2,2 - 3 - 4 100 - 112 28 60 28 60
  132 38 80 38 80
11-15 160 42 110 42 110
18,5 - 22 180 48 110 48 110
30 200 55 110 55 110
37 - 45 225 55 110 60 140
55 250 60 140 65 140
75 - 90 280 65 140 75 140
110 - 132 - 160 315 65 140 80 170
250 - 355 355 85 170 100 210
400 - 500 400 85 170 100 210

execution time customer :
runtime server : 0.045 seconds