The problems of pulse electrolytic power supply need to be solved at present

Nowadays, pulse electrolytic power supply plays a very important role in the development of electrolytic machining, and the rapid development of modern power semiconductor devices has created new technical conditions for the development of pulse power supply. In order to realize the engineering and industrialization of new pulse power supply and be widely used in production, the stability and reliability of power supply should be solved and the efficiency of power supply should be improved. At the same time, the maximum pulse current capacity and pulse frequency should be further increased. Therefore, the following problems should be further studied and solved.

Prevent overvoltage breakdown of power semiconductor devices In the high current fast shutdown t/DS will appear transient overvoltage, must control the overvoltage is less than the breakdown voltage value of the device. The main measures are to reduce the parasitic inductance of the loop and control the current rise rate. At the same time, the necessary buffer circuit is used to limit the overvoltage value, so as to prevent the overvoltage breakdown. &DS overvoltage increases with the increase of frequency rate, so solving this problem is also conducive to the improvement of power supply frequency.

Prevent overcurrent, overheating and burning of power semiconductor devices using a new and efficient cooling system and a microsecond fast current limiting device to expand the safe operating current zone of power semiconductor devices to prevent this failure.

Improve the anti-interference ability of power supply High-current semiconductor devices have large interjunction capacitance and are easy to introduce interference signals, so appropriate decoupling circuits should be adopted. When multiple channels are connected in parallel, they must be precisely arranged and strictly grounded to prevent interference from floating ground potential.

The experimental study of waveform distortion reduction shows that when the pulse current value is large and the pulse frequency is high, the pulse waveform transmission distortion is serious. The parasitic inductance of the loop is an important factor affecting the transmission distortion. Measures should be taken from the line layout and line structure to minimize the parasitic inductance of the loop, so as to minimize the waveform distortion, which is also conducive to improving the operating frequency of the power supply.

When the frequency of the pulse power supply reaches tens of kilohertz, self-excited oscillation is easy to occur, which is an important factor limiting the further increase of frequency, and this problem should be solved in line design and layout.

Improve the efficiency of the power supply the resistance current limiting scheme has a large heat loss and decreases the efficiency of the power supply. The operation time of the quick protection should be shortened as much as possible, that is, the instantaneous overcurrent time during the short circuit should be shortened to reduce the current limiting resistance value, reduce heat loss, and improve efficiency. Foreign advanced power supply adopts inductance current limiting, which can reduce heat loss and improve efficiency. Adopting an efficient cooling system to reduce auxiliary consumption is also conducive to improving the overall efficiency of the power supply. The opening and closing time of MOSFET is the shortest, so the cross area of current and voltage is the smallest when opening and turning off, the heat of the tube itself is the smallest, and because of its conducting resistance, the pressure drop of the tube after opening is small, so the heat loss of the tube itself is also small at this time. These two factors lead to the highest efficiency of MOSFET, therefore, in order to achieve the high efficiency of the power supply, under the condition of device capacity permits, MOSFET converter should also be the most used.

At present, in the small and medium capacity range, the high-frequency and narrow pulse power supply technology for electrochemical machining has been relatively mature, and is expected to be used in production in the near future. The large-capacity power supply also needs to carry out more systematic and deep applied basic research work, in the field of power electronics and thermodynamics to explore and master the law of fast turn-off and turn-on of large current, so as to further solve its engineering and technical problems.

Increase the current capacity to increase the current capacity can be multi-channel parallel or with IGBT commutation, the two schemes are not complicated, but the key is to solve a series of technical problems caused by the current increase, such as the above f/DS is too large, heat loss is too large, interference, self-excited oscillation and waveform transmission distortion, etc., the solution of these problems are conducive to the increase of current capacity.