Operation of power supply for resistance welding equipment, uses control circuit supplying pulses to synchronous rectifier connected to transformer secondaries

摘要

The power supply has coupled transformer secondaries (4b, 4c) and a synchronous rectifier with two paths (3a, 3b), each controlled by a secondary. First and second welding electrodes (5a, 5b) are supplied. A controller is provided for the synchronous rectifier. In controlling the rectification paths, the relative senses of primary- and both secondary windings are taken into account. Opposed electrode polarities are only blocked when the primary winding is controlled. The rectifier path instantaneously controlling opposed electrode polarities, is blocked before controlling the primary winding. This preferably occurs a few microseconds before controlling the primary winding. Components of the first and second rectifier paths are symmetrical in construction. The synchronous rectifier is connected to the two-section secondary circuit, at a central secondary tapping. Control of the first and second rectifier paths is achieved by symmetrical pulses. The controller (7) includes control logic, a pulse width generator and a gate circuit. These operate together to produce control pulses. An integrated circuit or discrete components, are used for control. The rectifier paths are controlled at a frequency of 1 kHz to 10 kHz. An independent claim IS INCLUDED FOR corresponding welding equipment.