The development of pulse electrolytic power supply

The pulse power supply technology is improved with the development of power semiconductor switching devices. Before the emergence of modern power semiconductor devices, the pulse power supply established by means of silicon diode rectification or thyristor turn-off can only obtain a small capacity, and the pulse current of lower frequency and wider sine wave type can not meet the needs of further development of pulse current electrochemical machining.

The development of modern power semiconductor devices has fundamentally changed this situation. The main characteristics of modern power semiconductor parts are large capacity, fast switching speed, and high current, high voltage and high frequency. In the 1980s, GTO (turn-off thyristor, also known as turn-off thyristor) developed to xio4 A, 8 kV, and the operating frequency of high-frequency GTO was increased by 2 to 3 times to 3kHz, which could replace SCR in a considerable range. At the same time, MOSEFT (power field effect tube) has been rapidly developed, the performance of the module can reach 1000V, 450A (maximum DC continuous current), its rapidness ranks first in all power semiconductor devices, the switching time can be as small as nanosecond, the frequency can reach 103kHz, the on-state resistance can be small so that it is easy to parallel, and the drive current is very small, stable and reliable. In recent years, the IGBT (insulated gate bipolar crystal tube) composite device developed on the basis of MOSFET is also maturing, and its operating frequency is a grade lower than MOSFET, 10~30kHz, but its current capacity is greatly improved, up to 1200A, 1600V. In the 1990s, power electronics continued to develop in the direction of improving their frequency characteristics, increasing capacity, increasing voltage and developing intelligent devices.

The above performance of modern power electronic devices such as MOSFET and IGBT gives the reality of realizing high current, high frequency and narrow pulse power supply, so that the new technology of high frequency and narrow pulse current electrochemical machining is expected to realize engineering application. According to the performance characteristics of the above power semiconductor devices, MOSFET converter is the best solution for 1~2kA ECM pulse power supply, which has high frequency, narrow pulse width, small tube consumption, good fast protection performance, simple power structure and low cost. At present, GT0 chopper power supply has been developed for thousands of amPs, and its performance is better than that of SCR chopper pulse power supply of the same capacity level, but the development of IGBT in recent years has given the reality of using IGBT converter, and its speed and economy will be better than that of GTO chopper pulse power supply. For tens of thousands of amPs pulse power supply is still more realistic SCR scheme. At present, the electrochemical machining pulse power supply using power semiconductor devices at home and abroad is in the engineering stage and has not been finalized.