On The Inverter Arc Welding Power System In The Saving Energy Products Of Oilfield

ABSTRACTSaving energy is not a ignored problem. And the problem looks very outstanding because, with the development of oilfield constructions, the demand on metal welding equipments is increasing rapidly, and is more considerable on society, and power consumption of arc-welding equipments is in great proportion. Taking the current state and features of arc-welding equipments into account and combining with the current study on arc-welding power supply, the paper develops a inverter arc-welding power source system in the saving energy products of oilfield in order to meet the needs of oilfield engineering construction for DC inverter arc-welding machines, that is, to fulfil the requirements of dynamic and static characteristics in terms of saving energy, reliability and improve the suitability of welding technology, which can serves the oilfields, and the society.The paper starts with the power supply for weld DC output of 400A,integrates the circuit structure, reliability, economic efficiency, and other aspects, uses IGBT as power electronic device to form a single forward inverter main circuit, and utilizes parallel type of lower power IGBT and parallels the double inverter arc-welding power sources to meet the need for high power output.The control circuit in the system adopts the pulse-width modulation (PWM) technique, and uses typical integrated circuit SG3525 as PWM modulator. The operational features of the system indicate that 1.PWM control mode is employed during normal operation, in which the inverter frequency is set of 20 kHz, to control the external characteristics at constant current. 2. on idle, using the voltage-feedback control makes PWM modulator output the pulse disjointedly with blocking-oscillation frequency lowered and the pulse width narrowed. Accordingly not only the no-load loss is less, but also the transformer is not easy to saturate. 3. during short circuit of welding arc, the control mode of short circuit dividing frequency is used to control short-circuit current. As a result, having adopted lower given value and the control circuit of minimum pulse width make the weld easy to arc, welding arc stable and welding performance fine. ABSTRACTTo insure reliable operation and safe motion, the soft start, the overvoltage, overcurrent, and overheating protection are installed at the system. And the magnet-coupling isolation device is used for performing good isolation between the main circuit and the control circuit, so that the main circuit is prevented from disturbing the control circuit, which makes the control circuit more stable and reliable. The development of the system have completed, and passed the test with high performance.