2014 IEEE XXXIV International Scientific Conference Electronics and Nanotechnology (ELNANO) 468 Direct Energy and Energy Storage Circuit Topologies of DC Power Supplies for Micro Resistance Welding Oleksandr F. Bondarenko, Pavlo S. Safronov, Iuliia V. Bondarenko Electronic Systems Department, Donbas State Technical University Alchevsk, Ukraine bondarenkoaf@gmail.com Volodymyr M. Sydorets Department of Gas Discharge Physics and Plasma Devices, E.O. Paton Electric Welding Institute of the National Academy of Sciences of Ukraine Kiev, Ukraine sydorvn@gmail.com Abstract — Direct Energy and Energy Storage circuit topologies of DC power supplies for micro resistance welding are analyzed and compared in the paper. The circuits’ basic parameters of energy quality are evaluated. The advantages of Energy Storage circuit topology are shown, which make possible to recommend it for use in micro resistance welding machines. Keywords — micro resistance welding; direct energy; energy storage; welding current; converter input current; total harmonic distortion; power factor I. INTRODUCTION Resistance welding is considered now as one of the most productive ways of welding. That kind of welding is simpler and has lower costs compared to other ones. Joining is performed by squeezing parts between electrodes, and then conducting electrical current through their interface. Generated heat in the welding area rises to melting temperature and causes a welded joint. Micro resistance welding deals with small-scale parts (< 0.5 mm). That type of welding is widely used in electronics and instrument-making for assembling miniature constructions and producing sealed packages of different devices [1]. So far as resistance welding is performed with electrical current, one of the most important parts of a welding machine is a power supply – source of welding current pulses. Rational construction of a power supply defines high technical and economical characteristics of a welding machine in whole [2]. Many works in the area of power supplies for micro resistance welding [3-6] concern the questions of building special converters that are able to regulate parameters of current pulses during a welding process to obtain high quality joints. An equally important question is providing energy for welding. There are two types of power supplies for welding: Direct Energy type and Energy Storage type [7, 8]. The first type consumes necessary energy portions directly from the power line during the welding process. The second type has energy storage in circuit between the power line and energy converter. The second one doesn’t take energy from the power line during the welding process. The aim of the work is to analyze circuit topologies of different types power supplies and to show their advantages and disadvantages. II. COMMON PRINCIPLES OF BUILDING DC POWER SUPPLIES FOR RESISTANCE WELDING In this work we focus on DC power supplies for resistance welding because of their essential advantage compared to AC supplies – higher precision of welding current regulation, which is very important for obtaining high quality welded joints [9]. The common structure of DC power supplies is given in Fig. 1. The Input Converter adapts parameters of energy from the power line for the next blocks of the circuit. The Output Converter provides needed parameters of current pulses during welding. Input and Output Control Blocks correct the converters’ operation according to sensors’ signals. Load power line ~ Input Converter Energy Storage Output Converter Output Control Block I, U Sensors Input Control Block Fig. 1. Common Structure of DC Power Supply for Resistance Welding We have a Direct Energy type power supply if Input and Output Converters are connected directly (dot line). We have an Energy Storage type power supply if the Energy Storage is added between Input and Output Converters and provides enough energy for creating at least one welded point without energy intake from the power line. III. CIRCUIT TOPOLOGIES OF DC POWER SUPPLIES FOR RESISTANCE WELDING Let’s analyze two circuit topologies of DC power supplies for resistance welding. The first one is typical, widely used circuit and the other one may be considered as a successful alternative. General settings for both power supplies are identical: - power line voltage – 220 V, sinusoidal (ideal); - power line frequency – 50 Hz; - amplitude of welding current pulses – 500 A; 978-1-4799-4580-1/14/$31.00 ©2014 IEEE