SU1431037A1 - Current pulse shaper - Google Patents

Abstract

The invention can be used to power windings that create magnetic fields, in particular to power the inductors of induction heating systems. The purpose of the invention is to increase efficiency. The generator contains a power source 1, in parallel with which, a chain of storage capacitor 13 and the primary winding of transformer 14 and chains of commutating skinny thyristors 3-5 and switching capacitors 6-8 are connected. Between the midpoint of the chain of storage capacitor 13 and the rest of the chains, discharge thyristors 9–11 are connected through choke 12. The additional winding of the transformer 14 through the diode 15 is connected in parallel to the storage capacitor 13. The device provides compensation for the S constant component and improves the harmonic composition of the output current. y / J 1 z.p. f-ly, 2 ill.

Description

four

OO

WITH

fig1

The invention relates to a pulse technique and can be used to power windings that create magnetic fields, in particular to power induction heating installations.

The aim of the invention is to increase the efficiency by reducing the constant component and the harmonic coefficient of the output current,

Fig. 1 is a schematic diagram of the proposed TOKaJ pulse generator in Fig. 2 — time diagrams of currents and voltages illustrating the operation of the device. The current pulse generator contains; power supply 1, load 2, com; mutating thyristors 3-5, connected to capacitors 6-8, whose connection points I through which are connected to the choke through the thyristors 9-11

i 12, the second one of which is connected; to the series-connected storage capacitor 13 and the primary winding of the transformer 14 connected in parallel with the source 1, to the secondary winding of the transformer 14, K

load 2 is connected, and the transformer winding is additional through diode 15

connected in parallel with a storage capacitor.

In Fig. 2, curve 16 is the current in the primary winding of the transformer, curves 117-19 are the voltages at the capacitors | b-8. ,

I The device operates as follows: IpasoM.

: In steady-state mode, the na: The storage capacitor 13 and the primary winding of the transformer 14 are transmitted by the current of the power supply source 1 caused by the energy losses in the load and other circuit elements. In this case, the current of source 1 is fed and flowing through the primary winding of the transformer 14 is magnetizing. At time t, the capacitors are charged with the fields indicated in Fig. 1.

At time t, the switching thyristor 3 is switched on and the combined discharge of the capacitor 6 and the storage capacitor 13 begins through the primary winding of the transformer 14 (curve 17). The current increases in the demagnetizing direction according to the sinusoidal law (curve 16). The capacity of the storage capacitor 13 is significantly greater than the capacity of the capacitor

-

ten

15

20

25

thirty

35

40

45

50

55

6. Therefore, when co-discharging, the voltage on it remains almost constant and basically only the capacitor is discharged 6. Once discharged to zero, the capacitor 6 is recharged first under the action of the energy of the storage capacitor 13, and when it reaches the voltage of the storage capacitor 13 under the action of the energy stored in the inductance of the load 2 and the inductance of the dissipation of the transformer 14. This changes the sign of the voltage on the primary winding of the transformer 14, and the current in it begins to decrease. At time t, the voltage on the additional winding reaches the voltage on the storage capacitor 13 and the diode 15 opens. The current from the primary winding intercepts into the additional winding and through the diode 15 recharges the storage capacitor 13. In this case, the switching thyristor 3 de-energizes and locks the voltage on the capacitor 6 at this moment is equal to the sum of the voltages of the storage capacitor 13 and the primary winding of the transformer 14. When the number of turns of the primary and additional windings of the transformer is 14, for example ix across the capacitor 6 at twice the voltage on the storage capacitor 13. By so mere.zar storage capacitor 13 current through the diode 15 decreases, and the time t it falls to zero. At the same time, the diode 15 is closed.

At time t, the thyristor 10 is opened and the capacitor 7 is recharged through the choke 12 and the primary winding of the output transformer 14 (curve 18). A current flows through the circuit in the direction magnetizing the transformer 14 (curve 16). Perezar capacitor 7 occurs according to the oscillatory law. At time t, the current through the thyristor 10 drops to zero and the thyristor closes. At time tj-, the switching thyristor 5 is opened and the recharging of the capacitor 8 begins through the primary winding of the transformer 14 (curve 19). The current through it increases according to the sinusoidal law in the demagnetizing direction (curve 16). When the voltage across the capacitor 8 reaches a voltage equal in magnitude to that of the storage capacitor 13, the total voltage at

clipping to the primary winding of the transformer 14, becomes zero, with the maximum current in the circuit. Next, the capacitor 8 is charged under the action of the energy stored in the load inductance 2 and the leakage inductance of the transformer 14, and at the time point tg reaches a voltage of twice the voltage of the storage capacitor 13. At this point, diode 15 and the current from the primary winding is intercepted into the additional winding of the transformer 14. This closes the thyristor 5 and stops the charge of the capacitor 8. The current through the diode 15 decreases as the accumulator capacitor 13 charges and at the time t of the current dropping it closes about zero At time tg thyristor 9 is opened and commences recharging the capacitor 6 through the throttle 12 and the primary winding of the transformer 14 (curve 17). The recharge current oscillates with oscillatory law (curve 16) and at the time tg of the current dropping to zero, the thyristor 9 is closed. In this case, the capacitor 6, recharging through the choke 12 and the primary winding, creates a current, a magnetizing transformer

1A. Due to the power of the droplets 12 and the inductance of the load 2, the capacitor 6 is recharged almost to the value of the voltage equal to the initial

At the time t, the switching thyristor 4 is turned off and the recharging of the capacitor 7 begins (curve 18). Through the primary winding of the transformer 14, a current is flowing in the demagnetizing direction, which is sinusoidally changing (curve 16). When the voltage of the capacitor 7 reaches the storage capacitor 13, the current in the primary winding becomes maximum and the voltage on the winding of the transformer 14 changes its sign to the opposite. Next, the capacitor 7 is charged under the action of the energy stored in the load 2 and the inductance dissipated by the transformer

torus 14, At the time t, the voltage on the auxiliary winding of the transformer 14 reaches the voltage of the storage capacitor 13, and the voltage on the capacitor 7 is double the voltage of the storage capacitor 13, at this moment open 10

j 25 thyristor 30

The diode 15 and the primary current are intercepted into the additional winding, charging the storage capacitor 13. The charge of the capacitor 7 stops and the voltage on it remains constant until the opening of the thyristor 10. The switching thyristor 4 is de-energized and closed. The current through the diode 15 decreases, and when the current drops to zero at time t, the diode 15 closes.

At time t, the auxiliary thyristor 11 opens and the capacitor 8 recharges through the choke 12 and the primary winding of the transformer 14, forming a magnetizing current half-wave (curves 16 and 19). At time t, 4 the capacitor 8 recharges and the thyristor 11 closes. The absolute value of the capacitor 8 is almost equal to the initial value,

B time t opens

3 and further, the processes are repeated. The processes occurring during the operation of the commutating T1fistors 3-5 as well as during the operation of the thyristors 9-11 are completely identical1-gchny.

From the description of the principle of operation of the generator, it can be seen that the primary winding of the transformer 14 carries current in the demagnetizing and magnetizing directions. The area bounded by the demagnetizing current curve

40

45

5 (curve 16) in the range of the conducting thyristor 3, is equal to the area under the magnetizing current curve in the recharge interval of the capacitor 7, since the magnitude of the change in charge of the capacitors 6 and 7 is equal to (curve 17 and 18). The demagnetizing effect of the discharge current of the storage capacitor 13 and the capacitor 6 is completely compensated by the magnetizing current of the capacitor 7. However, the current flows through the additional winding of the transformer 14 in the demagnetization direction of the diode 15 The demagnetizing effect of this current is compensated for by the current of the power source 1 flowing in the 55 magnetizing direction through the storage capacitor 13 and the primary winding of the transformer 14 (curve 16),

50

about rmu l and

five .

goiter

rete n i

Claims (2)

1. A current pulse generator containing a power source, a load, N chains of scrubbing thyristors, the anodes of which are connected to the positive power supply bus, and the a-cathodes to the first plates of N capacitors, the second plates of which are connected to the negative power supply bus, switching points of the commutators thyristors and capacitors via bit thyristors are connected to a choke, characterized in that, in order to increase the efficiency by decreasing U31037 neither the constant component nor the harmonic ratio of the output current, the second output of the throttles is connected to the connection point of the storage capacitor connected in parallel and connected in parallel to the power source and the primary winding of the transformer, the secondary winding of which is connected to the load. 2. The generator according to claim 1, characterized in that the transformer has an additional winding connected via a diode in parallel with a storage capacitor. °  t