SU575739A1 - Device for additional charging of switching capacitor - Google Patents

Description

(54) DEVICE FOR COMMUNICATING SUPPLY

CONDENSER

The invention relates to a converter technique and can be used in autonomous thyristor inverters with adjustable frequency and magnitude of the output voltage.

Inverter circuits are widely used devices for charging commuting capacitors, providing high switching capacity and improving the weight and size parameters of inverter switching devices.

In most cases, such devices consist of a constant voltage source, throttle and thyristors connected in various ways to switching capacitors.

In the independent inverter 1, a thyristor subcharge of the switching capacitors is applied. In this scheme, auxiliary thyristors are used for charging and switching capacitors, the anodes of three thyristors, the cathodes of which through a choke are charged and connected to the negative terminal of a single charge source, and the cathodes of three other thyristors of the charging power, the anodes of which are connected through another throttle charge to the positive terminal of the other source of the charge, connected to three other commutation chondinas (ators. The disadvantage of the device is its instability in transient modes.

The closest to the proposed technical essence and the achieved effect is device 2, in which serially connected switching capacitor and choke are included in the diagonal of a bridge circuit consisting of four charge thyristors. The anodes of two thyristors of the bridge circuit, the cathodes of which are connected to the lining of the switching capacitor and output pins of the switching drossel, are connected to the positive terminal of the constant voltage source of charging, and the cathodes of two other thyristors of the bridge circuit, the anodes of which are connected to the indicated lining of the switching capacitor and the indicated by the output of the commutating throttle, they are connected to the negative terminal of the charge source.

Claims (2)

The charging is carried out after the commutator capacitor is recharged by switching commutator circuit current by switching on two thyristors of the opposite arms of the bridge circuit. At the same time, the processes follow the laws of oscillatory circuits, the switching capacitor discharges before voltage, high voltage of the charging source, and consequently, the thyristors are loaded. yes shut down securely. A disadvantage of the charging device of the present inverter is the following. When the inverter operates, the mode occurs when the voltage on the switching capacitor, after being recharged with its switching circuit current, is close to or equal in magnitude to the voltage of the charging source. As a result, the reverse voltage is not applied to the charge thyristors, their turn-off time increases significantly and may exceed the time provided by the circuit. This leads to a short circuit of the nodzar source and at the next pod of the de switching capacitor and the breakdown of the inverter switching. This phenomenon reduces the reliability of the inverter circuit and limits the maximum inversion frequency. The aim of the invention is to improve the reliability of the operation of the thyristors of the charging of the inverter switching capacitors. The goal is achieved by the fact that between one output of the thyristor bridge and the choke connected to the source of direct voltage, an additional thyristor is connected, in parallel with which is connected a series circuit from a resistor and a low voltage source. A schematic of the proposed device for charging a switching capacitor is shown in the drawing. A constant voltage source 1 and a filter capacitor 2 are connected in parallel, their common point is connected to a choke 3. A bridge circuit on thyristors 4-7 with switching capacitor 8 is switched on in the same diagonal by source between source 1 and cathode of additional thyristor 9, in parallel with which a circuit from a low voltage source 10 and a resistor I. For controlling the thyristor 9, for example, a starting circuit based on dynistor 12 and a capacitor 13 can be used. The device operates as follows. Let the switching capacitor be charged with the polarity shown in the drawing. At some point in time, the switching process in the inverter power circuit begins. At the same time, control pulses are applied to thyristors of charging 4, 6. At this, capacitor 8 is recharged by current of switching circuit 12 and current of charging source through circuit: voltage source 1 - choke 3 - resistor 11 - voltage source 10 - thyristor 6 - capacitor 8 - thyristor 4 - minus voltage source 1. Since the value of resistor 11 is chosen sufficiently large, the current of source 1 is several times less than current 12, and switching capacitor 8 is recharged by current Ij. When current 17 drops to zero, the capacitor is slowly recharged by current 11 through a resistor 11 and a low-voltage source 10. When the thyristor 9 is turned on, an oscillating circuit is formed: plus source 1 — choke 3 — thyristor 9, b — capacitor 8 — thyristor 4-minus source 1. At the same time, the capacitor 8 of the dispenser until the voltage is higher than the voltage of the source 1. At the end of the dispenser of the capacitor 8, the voltage of the source 10 in the opposite direction is pressed to the thyristor 9, ensuring its reliable switching on. The thyristor control pulses 9 are formed by an inverter thyristor control system or a starting circuit on a dynistor 12 and a capacitor 13. Formula of the invention A device for charging a switching capacitor included in the diagonal of an alternating current of the thyristor bridge, having terminals for a constant voltage source connected to the capacitor of the filter one of which is connected to one DC output of said bridge, and the other is connected to a choke, characterized in that, in order to increase the reliability Between the other terminal of the DC thyristor bridge and the free kontso.m upo.m mentioned choke included additional thyristor, which is connected parallel to the series circuit of a resistor and a source of EMF. the polarity of which is opposite to the polarity of the additional thyristor. Sources of information taken into account in the examination: 1. USSR Author's Certificate No. 289403, cl. And 03 K 17/66, 1970. 2. French patent “Yg 1404651, cl. H 02 M, 1971. ABOUT / 2 but / And