Research On 100kA/80V DC Power Supply Scheme For Shell Furnace

The shell furnace is a must-have for casting precious precision metal parts.Usually,the power supply used in such equipment is low-voltage and high-current,which requires the use of a rectifying device to change the high-voltage AC of the grid into the required low-voltage DC.Thyristors are still the largest single-tube capacity in power electronic devices,so in DC power supplies with currents above 10 kA,thyristors are still used as main power devices.At the same time,as various power electronic converter devices continue to be put into industrial production,harmonic pollution of the power grid is becoming increasingly serious.In this paper,in order to overcome the shortcomings of large power DC power supply and large harmonics injected into the power grid,the power supply scheme can be analyzed and compared first.To reduce harmonic pollution,24 pulse rectifier transformer and rectifier are selected.Cabinets,each transformer uses epitaxial delta connection on the primary side and four three-phase bridge in-phase anti-parallel structure on the secondary side.For the first time,epoxy cast dry rectifier transformer is used to obtain DC power supply with total output of 100kA/80 V.Use a pure water cooler to dissipate heat from the rectifier cabinet.The whole system is also designed with voltage and current sampling and conditioning circuits and various protection circuits.In order to achieve a high degree of intelligence of the power supply,the system is designed with a PLC and a host computer detection unit.The control part uses the combination of DSP and CPLD to complete the generation of 24 trigger pulses,dynamic hot standby,data monitoring and processing,output pulse and input synchronous voltage phase sequence adaptive,closed loop adjustment.Finally,the software and hardware design of the prototype is simulated and debugged to verify the correctness of the design and the reliability of the power supply.