CS204264B1 - Connection for increasing the current of the idle sources with the rectifying elements - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a circuit for increasing the open circuit voltage of rectifier elements, in particular for arc welding, consisting of a transformer and a rectifier as a current source.

Hitherto, a higher open-circuit voltage for easy arc ignition has been obtained, for example, by using a source already at the desired higher voltage or by some indirect method, in which the increased voltage supplied a special winding of a power transformer or a special low power transformer.

When using a higher voltage source, the transformer of this source is considerably heavier and the power factor of the source is low. The use of indirect methods, in turn, is labor intensive in the manufacture of winding parts.

Essentially, the present invention eliminates these drawbacks by providing an incremental capacitor between the arbitrary output pole of the rectifier and the secondary winding of the source transformer.

The connection according to the invention makes it possible to significantly reduce the weight of the power supply transformer of the rectifying source, since this reduces the required power of the transformer and also the weight of the entire welding source. The power factor of the source will also increase. The application of the invention allows easy arc ignition and maintains the stability and elasticity of the arc during welding.

The attached drawing shows examples of wiring according to the invention. In Fig. 1 single-phase and Fig. 2 three-phase connection.

Fig. 1 shows an example of a single-phase resp. two-phase DC power supply. The power transformer T is connected to a rectifier, which consists of two controlled and two uncontrolled rectifiers. A boost capacitor C and a second boost capacitor C1 are connected in parallel to the outputs V1 and V2. A suitable transformer secondary winding terminal T is connected between the two capacitors C and C1. The capacitors are connected via charging and discharging resistors respectively. inductance.

A choke L is connected upstream of the output VI. FIG. 2 shows an example using a power supply with a three-phase transformer T and a rectifier B. Further wiring is the same as in FIG. 1. In both embodiments, one of the capacitors C or C1 can be omitted. In this case, a smaller no-load voltage increase with a large ripple is achieved.

When both capacitors C and C1 are connected, not only a higher voltage is achieved, but also a more suitable output waveform between terminals V1 and V2. Thus, essentially the sum of the voltages at both capacitors C and C1 is obtained between terminals V1 and V2.

With the circuit according to the invention, directly controlled rectifier elements of the power welding rectifier B can be suitably used to form a voltage doubler.

The capacitor C may be charged from a voltage source utilizing the power rectifiers of the source or from a separate voltage source. In principle, voltage multipliers, which charge capacitors C or C1 connected to the output terminals of the power supply, are used to increase the voltage. A limiting element (resistance or inductance) may be located anywhere in the charging or discharging circuit. It is particularly advantageous to use a circuit rectifier for this purpose.

The source transformer A is designed only for the required welding current but only for the voltage necessary to maintain the output voltage of the welding source at the normalized welding voltage. This reduces the power of the transformer and hence its weight. Due to the lower secondary voltage of the transformer, the controlled rectifier B can be more economically controlled for the same welding output current of the source. This greatly increases the efficiency and efficiency of the welding machine. For the same reason, a choke with lower inductance is sufficient for the same current smoothing. This further reduces the weight of the welder. At the same time, the level of interference caused by the welding machine is reduced. By using the circuit according to the invention, it eliminates the need for so-called ballast loads in the controlled rectifiers of the arc welding machines, thereby reducing the idle losses.

The use of the circuit according to the invention is particularly advantageous for arc welding sources.

Claims (3)

SUBJECT OF THE INVENTION 1. An open-circuit voltage boosting arrangement for rectifier elements, in particular for arc welding, consisting of a transformer and a rectifier as a current source, characterized in that an increase capacitor (C) is connected to the source (A) between any rectifier output pole ( B) and the secondary winding of the transformer (T) of the source (A). Connection according to Claim 1, characterized in that a second capacitor (Cl) is connected between the transformer secondary winding (T) and the free output pole of the rectifier (B). 3. Connection according to Claims 1 and 2, characterized in that the capacitors (C, Cl) are connected to a DC voltage source.