DE1438888A1 - Arrangement for resistance-braked DC motors - Google Patents

Description

Arrangement for resistance braked DC motors *

Be and brake arrangement »known with regulating resistors for DC motors» freely which after interruption of the Supply voltage to the armature and maintenance of the voltage of the excitation windings a shunt resistance between the Anchor terminals is switched. Such arrangements are used in particular for speed margins. Drives of freerader-excited motors, a motor speeded with such an arrangement works as a generator> where he ^ tle-ine energy takes from the moving masses. If the resistance of the brake assembly remains constant, will be in the course of the deceleration the intensity of the current flowing through the resistor as well as decrease the braking torque applied to the motor,

By gradually increasing the braking resistor using

Relay briefly streaks, you can temporarily "output" reach braking torque again; switching on these beiais Always has brutal consequences because the moment of resistance is sudden

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disappears; these poles take with the electromotive Force of the motor acting as a generator, its speed diminishes, from "

The present invention aims to provide a brake assembly, which controls and allows this inconvenience, the braking torque practically up to the standstill of the engine to receive o

The arrangement according to the invention is characterized in that at least one rectifier bridge during the braking process is connected in series with at least one braking resistor at the terminals of the motor armature, with the voltage of the bridge during the braking process and that of the motor rotating as a generator adding up to through the bromine resistor (s) to send a current to a circuit comprising the armature winding and the rectifier bridge or bridges with the corresponding resistor or resistors in such a way that the braking torque is maintained regardless of the speed of the motor ₀

The rectifier bridge can be independent of the supply bridge of the motor or coincide with it, whereby Umschal t devices allow their insertion according to a polarity that matches the resistance circuit; the two Bridges can also be connected in parallel, each feeding through its braking resistor *

Further characteristic features of the invention are set out below in the description, for example, wherein the Figures serve to explain the examples.

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Show it :

Fig. 1 is a diagram of a classic resistance brake arrangement a DC motor,

2 shows the diagram of a brake arrangement according to the invention, which is adapted to the scheme according to Pig 1, with two equal judges' bridges,

3 shows the circuit diagram of an arrangement with only one rectifier bridge for feeding and braking,

Figo k an embodiment analogous to FIG. 3 »Rait reversal of current flow in the field winding,

Fig. 5 shows the scheme of an emergency braking _f

FIG. 6 shows the arrangement according to FIG. 2 with feeding by induction regulator "

All figures are shown in simplified form with a single-phase supply} it goes without saying that the invention also includes all of them multiphase arrangements, however the circuit of the rectifier used is done,

According to FIG. 1, the armature 1 of a direct current motor is peened by a rectifier bridge 2, for example by means of diodes in a burr circuit, which are connected to a current transformer 3, via the main switch k with the terminals 5 and 6. A slide 7 located on the secondary winding of the transformer allows the supply voltage and thus the motor speed to be changed. The runner 7 is pushed by means of a servo motor 8, wherein

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the servomotor 8 is actuated by means of a changeover switch 9 or by any other manually or automatically operated arrangement which allows the servomotor to be rotated in this or that direction in order to move the slide 7 of the transformer 3 accordingly.

The separately excited excitation winding 10 of the motor is a DC bridge 11 split. This is through interposition a contact relay 12 connected to the general supply network or another power source. The line feeding the excitation winding can also be used to feed the servo motor »

A braking resistor 13 is connected to the armature 1 terminals via a braking relay l4.1. To the drawing do not overload j all interlocks and safety devices has been omitted, in particular the locking of the main relay 4, which can only be switched on can, when the slide 7 of the transformer is in the zero position, the excitation is present and none of the , Safety devices has been triggered (magneto-thermal Relay, Buchholtζ, thermostat etc.).

Starting from the known arrangement, one arrives at the execution according to FIG. 2, in which all of the aforementioned Elements are shown in turn.

A DC bridge 15 is connected to the braking resistor 13 in Series switching connected. This bridge with, for example, in single-phase Grätz circuit mounted diodes, such as the feed bridge 2 of the motor, which does not rule out other connection possibilities, is of opposite polarity to that one

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the supply bridge of the motor and is connected to an isolation transformer 16 to avoid any current transfer between the two bridges. In particular, the supply bridge 2 of the motor can be connected differently than that of the supply for the brake 15 t The primary side -des Isolation transformer 16 let between the slide 7 and the End E of the secondary winding of transformer 3 connected »

The excitation coil Ik of the braking relay with an opening contact 17 t actuated by a polarized relay 18 in the shunt of the armature 1 is fed via an auxiliary power source (not shown).

The arrangement works as follows;

If a brake command is issued, be it by manual control, be it automatically through safety elements in the system, on the one hand, the servo motor 8 brings the slide 7 of the transformer 3 In the zero position, which on the one hand the supply current of the motor is reduced by the rectifier bridge 2 or makes it disappear and on the other hand the brake relay lJf.l. closes. Am by the sum of the electromotive force The current caused by the motor rotating as a generator and the voltage of the rectifier bridge 15 now circulates in the braking resistor 13 and in the armature and maintains the braking torque. The value of this moment is

C _p . KI f

Mean: No motor constant,

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I is the current in the armature and Lp is the value of the excitation current.

To .aen course dee to track flow better, one can consider two operational extremes:

a) The motor follows the gradual drop in voltage, so that no braking arrangement of any kind is necessary. Provided that the two rectifier bridges Z and 15 have the same circuit and that the transformation ratio of the isolation transformer 16 is the same. 1 (whereby none of these conditions are absolutely necessary), a constant voltage is established at the terminals of the resistor 13, which is equal to that of the transformer 3 and equal to the voltage U at full speed. This-

gives a current U, where R means the braking resistance value,

R ■. -

This current runs through the entire Speisegloichrichterbrüeke 2.

b) The motor has a very high inertia and runs practically at the same speed welter, the slide 7 of the transformer being pushed into the zero position by the servo motor 8. At the moment the relay lk is switched on, the intensity of the resistor 13 will still flow completely through the (xleiehrlchterspeisebrücke 2), as in the previous case.

When the motor is running as a motor, the voltage is applied to the Clamps of bridge 2 higher than the counter-electric rotor Power of the driven motor by a value, tier is equal to the product of the armature resistance and the normal

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stron. The current flowing through the braking resistor is U

If the voltage at the terminals of the rectifier bridge 2 as a result of the movement of the slide 7 of the transformer decreases towards the hullage and a value is reached which is below the electromotive force of the motor the amperage in the braking resistor 13 is withdrawn from the motor circuit. The electromotive force of the motor », which is called The generator is running, will continue to remain constant, (the speed remains essentially also constant and becomes the voltage Add 15 from the rectifier bridge, so that the current will rise to the value 2. U. In other words, increases

R. the momentum gradually in order to reduce the braking force at the start of braking

double the braking torque · to achieve.

If the braking resistor has been calculated in such a way that the normal current flows in it under a continuous maximum supply voltage of the motor, the braking torque, when the slide 7 is in the zero position, will have twice the value of the normal torque ₀

In practice, the engines are operated between these in both of the aforementioned extreme cases. The tension on the clamps of the armature decreases progressively, becomes zero and then turns back. At standstill it reaches a value which is equal to the product of the braking current and is the armature resistance.

At this moment, the polarized relay 18 is on

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The reason for the effect on contact 17 is the brake relay l4ul open, which means that the motor can be taken along as a result of the dee Current supplied via the rectifier bridge in the opposite direction of rotation is avoided. This activity of the polarized relay can also be done by any other mechanical or electrical equivalent element, which prevents the motor from stopping and rotating in the opposite direction, e.g. by means of a centrifugal relay.

The above-described arrangement is of particular interest in those industrial circles in which the drive by means of high moments of inertia or moments of inertia (QD) takes place and which no impacts during the braking process allow, for example in the paper industry. This arrangement secures even at low speeds thanks to the current injected through the brake rectifier bridge 15, a substantial * braking torque.

It should be mentioned that the duration of the effect of the isolation transformer Xo έ-Ehr is short, which allows it to be significantly undersized in terms of performance. In Fig. 3 an economically interesting variant of the arrangement is shown in which the supply bridge is also used to be switched into the braking resistor 13 during the braking process.

Dex · Isolationftx'aneformator 16 is then unnecessary. if the brake command is given, one closes the circuit of the relay 19, which on the drai changeover contacts 19 * 1 19.2 and 19.3 acts, the first feeding the

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Rectifier bridge 2 between the end E and the slide 7 of the Traneforraatore switches and the servo motor 8 the Slide 7 moves towards the zero point.

The other two contacts 19ο2 and 19 * 3 control the reversal of the current of the rectifier bridge 2 in the armature 1 and cause the onset of the braking resistor 13 in the circuit the latter »

The basic operation is the same as that geiuäss the arrangement Figo 2. The stoppage of the engine, which can be determined by means of the polarized relay 18 or by other equivalent means λ beiuplelsweise caused the return of the engine to its normal operating position by the braking resistor 13 from removed from the circuit and the rectifier bridge 2 is again connected to terminals 7 and 8 of transformer 3 «

In a second, in Fi _1;. The variant shown here is the reversal of the current in the excitation circuit instead of in the armature, which is permitted, use smaller size changeover switches. The switch 19.1 controls, as in the previous case, the reversal of the terminal dor ( "le 3. chri CHT orbrücke 2 to the transformer 3 * Two Umsteuerkontakte. 19. ¹ ^ and 19" 5 allow the current direction in dor excitation winding 10 to reverse, while an opening contact IO.6 short-circuits the braking resistor 13 during normal operation and brings it into the armature circuit as soon as, as explained, a braking command is issued

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Relay 18 when the motor is at a standstill, the supply coil 19, which acts on all the aforementioned contact © ηηύ üi @ Rückkefir the system as Mofcorenaniage allows. In this operation, the direction of the »current _9, which from üh rectification rbrtick® _s in the winding does not change, but the polarity of the. Anchor _t w & nn ä®r ¥ ®chs®i ύ & τ direction in the excitation winding takes place" «,

This just described an.OTdn.ung varlasgt certain fe © lti3i? JassisalKs @ n during d @ a Ums tau®stns d © s Stroaass i, n , around the Diapefo.br@rai®adnahme Motors, -ηηύ d £ © ν β ras ©! more Dastsa _geh.8r <sn be "d®pi © lst.'Qis @ the Sfsffs d®_e HanptssSialters, bcTos ^ dis UmisöfeCTsag dor Sp @ <Lsvmg- of * Gleiclirichterbrücke done, and resistors inserting before Bntlads- or diodes _o

If you make an immediate or emergency braking i / ill, use an arrangement according to FIG. 5, which is a connection the fillings vegetables the Fig, 2 and 3 represents »

The rectifier bridges 2 and 15 ”and the braking resistor 13 with its relay 1h can be found there again. An additional braking resistor 20 can be switched into the circuit by means of the reversing contacts 19.2 and 19 · 3, which contacts in the circuit also determine the current direction of the rectifier bridge 2; change the incoming current.

Two closing contacts 19-6 and 19 »7 allow the connection the rectifier bridge 15 to the Bndklemmsn 0 and B of the transformer 3i so that this bridge is under fixed

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Voltage is applied. The contacts ΐΛ.1 and 19 "1 - 19 <> 7 are controlled by their coils Xh and 19, which are excited when the braking command is issued by the contact 17, as described in the previous examples _β

When the command to brake quickly is given, the changeover contact 19.1 connects the rectifier bridge 2 to the terminals 0-E of the transformer 3, while the reversing contacts 19.2 and 19 * 3 reverse the direction of the current in a circle and switch on the resistor 20. At the same time, the normal braking switch Xk closes and also includes the normal braking resistor 13, while the contacts 19 * 6 and 19 * 7 set the brake rectifier bridge 15 tinter voltage.While the rectifiers are generally designed for starting torques, their value. is twice as large as the value of the normal torque required - _% if you have a braking resistor stand of the value R, so that I «U, where

η c

I denotes the normal current, but no such arrangement

special XTeberdimension your rectifier required.

Further variants can be derived from this system type especially combinations with reversal of the polarities of the excitation winding.

Instead of the rectifier bridges by fixed transformers with variable transformation ratio you can also feed them through induction regulators. The application of this type of supply and the control of the

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Engine speed, as shown in Fi / j «6 illustrates approaches, the example of the embodiment geraäss Fig. 2 _O

The induction regulator comprises a stator winding in two parts 21 _o 1 and 2I ₀ 2, which are connected in series and the end E of which is connected to a terminal on the primary side of the isolation transformer 16 of the arrangement. The other terminal of this transformer is connected to the free end of the rotor 21 "3 of the controller, which takes over the function of the slide 7 in the case of being fed by a transformer with variable transmission. Working with this system is exactly the same as working with the system according to Flg «2,

All the arrangements described above can of course also be connected to a supply with induction regulators will. They can also be used in the case of magnetic regulation of the speed of the motor. the Rectifier bridges are then either fed by a system of saturated self-induction coils or by means of transducers, the control current in this Fall controls the braking torque «

T2s are also familiar with the circuits set up in all figs combined with each other in different ways and Veiso with the various elements that correspond to "However, always using a Gleiehrichterbrtteke in the Breras resistance circuit. In particular, what has been said also applies to engines with through Permanent magnets of excited winding, as well as composite

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or series engines. For the latter, at the moment of braking one has to determine the meaning of the excitation development in relation to the person of the armature, with the supply rectifier 2 both for supplying the motor and for braking serves »

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Claims (6)

K38888 45/65 claims 1. Arrangement for resistance-braked DC motors in Composite circuit or series circuit with external excitation, which are fed by static rectifiers, characterized in that that at least one rectifier bridge (15) during the braking process with at least one braking resistor (13) to the Terminals of the motor armature (1) is connected in series, whereby the voltage of the bridge (15) during the braking process and diejerLge of the motor rotating as a generator in order to create an armature winding (1) through the braking resistor (s) (13) and the rectifier bridge or bridges supply a current to the circuit comprising the respective resistor or resistors to send in such a way that the braking torque is maintained regardless of the speed of the motor. 2. Arrangement according to claim 1, characterized in that the rectifier bridge (2), which in the resistance brake circuit is to be switched, the motor (1) feeds, with switching means (-19 · 2; 19 * 3) whose switching on on the occasion of the braking process it and cause the current to be reversed in the supply circuit of the armature (l) (Fig. 3). 3- arrangement according to claim 1, characterized in that the rectifier bridge (15) on the occasion of the braking process its current into the armature and through its braking resistor (13) sends parallel to the feed bridge (2) controlling it, the feed bridge (2) by means of switching means (19.2; 19-3) in 9098 1 4 _y / 0 1 5 8 U38888 45/65 D correspondingly via an additional resistor (20) is connected to the armature (1) of the motor (Fig. 5) 4. Arrangement according to claim 1, characterized in that means (19.1; 19.4; 19.5; I9.6) are provided to control the current direction reverse in the excitation winding (10) and thus change the polarity of the armature (1) when braking (Pig. 4). 5. Arrangement according to claim 1 and 4, characterized in that at the moment the engine comes to a standstill, the switch (I7) and / or the contacts (14.15 19.1J 19.2; 19-3; 19.4-19.6) in Circuit of the braking resistor by means of a polarized heater (18) or corresponding electrical or mechanical equivalent Organs are returned to their normal position. 6. arrangement räch claim 1, characterized in that the Rectifier bridge switched on in the braking resistor circuit (1,15,15) (15) through a transformer (16) variable transmission ratio, e.g. through the interposition of a Isolation transformer (16) or a corresponding control arrangement or directly under constant voltage, sptesen (Fig. 2 and Fig. 6). Public limited company BROWN, BOVERI & CIE. 9098U / 0158