Micro resistance welding is effective way to reliably join small-scale parts in electronics industry and instrument-making. High quality welded joints are obtained by coordinating welding current and electrodes squeezing force profiles. The decisions for minimizing inertia of welding machine units proposed in the paper allow achieving accurate coordinated control of current and force profiles.

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.

In order to formulate requirements for electrical equipment for a prospective hybrid welding process Plasma-MIG, the following studies were carried out. The theoretical analysis of the influence of the plasma discharge temperature with non-consumable electrode on the melting of the electrode wire was carried out. The dynamics of the melting of the electrode wire and dynamics of circuit with consumable electrode arc were been investigation. The estimation of maximum values of the temperature of plasma have been made. Influence of the MIG process on the volt-ampere characteristics of the plasma discharge have been studied. These results were used for carrying out the technological experiments.

This paper proposes a fault-tolerant solution for the three-phase DC-AC converter using a modified impedance source Boost inverter. Besides the additional modified impedance source, the solution is based on the reconfiguration of the topology to maintain the desired operation in case of an open circuit failure mode of a power device. The proposed topology presents important features such as a Boost capability to operate under fault condition and avoid extra active power devices in normal operation (without failures). Besides that, the circuit does not require dead times between the switches of each leg, which increases the reliability of the topology. Regarding the control solution for this converter, it is adopted a closed-loop current controller combined with a vectorial voltage modulator. Since this modulator is also function of the shoot-through, it will be possible to recover the amplitude voltage space vectors due to open-circuit failures in power devices. The combination of these elements allows to obtain three-phase balanced AC currents with reduced total harmonic distortion even in fault-tolerant operation mode. The fault-tolerant performance of this solution is confirmed through several simulations and experimental results.

An algorithm was developed for solving two-dimensional axially symmetric elliptic problems of skin effect modeling in a two-phase medium (electrode-biological tissue). The numerical calculations of high-frequency current flow in the electrodes of electrosurgical instrument and biological tissue were carried out. Developed mathematical model allows for analyzing the electromagnetic processes during electrosurgical intrusions. The mathematical model was compared with the experimental data on retina to choroid welding-up.