Current power supply
HIGH PRECISION POWER SUPPLIES
EVPÚ, j. s. c., developed and manufactured high-precision high current power supply for the research laboratories of the Joint Institute for Nuclear Research (JINR, Dubna, Russia), based on the defined very rigorous requirements for accuracy of output current setting and stability, or based on a defined time-dependent current characteristic. These sources are static power converters that are designed to provide a time and temperature stable supply (or cyclic dynamic supply) of electrical current to the deflection electromagnets and the electromagnets providing beam focusing in a transport system of the particle accelerators.
The design of converters for static mode of operation is based on static power converters with partially digital control system.
Output parameters are regulated using active semiconductor devices under switching mode operation. Power supplies are suitable for stable powering of magnetic circuits in particle accelerators. Output parameters are adjustable using the keyboard or through the appropriate serial communication interface (usually RS485). Resolution of reference values can be 14 or 16 bits. These current sources can also be used to power superconducting magnets, while also providing unique protection for identification loss of superconductivity of the load magnet ensuring its safe demagnetization and magnet disconnection. Output current can be a reversed by mechanical or motor reverser. Converters are designed with the stability of output current lower than 100 ppm, depending on various failure factors (change in ambient temperature, cooling liquid temperature change, step change of input voltage, etc.).
Special group of current supplies for dynamic mode operation are pulsating output supplies that are designed to power synchrotron magnets. These converters provide a regular repetition of the current pulse with a precisely shaped rising and falling edge and high dynamic accuracy.
Energy taken from the magnetic circuit during the demagnetization is recovered. This feature ensures that the main network only covers operating losses in the converter and the load chain. Nowaday in EVPU, two platform of current supplies with energy recovery opportunity are being developed.
The first platform is more efficient at lower output voltage levels, and the energy during magnet demagnetization is stored in the appropriate inverter circuits designed for this purpose, only the losses in the converter chain and the load are covered from the power supply network. The second platform is more efficient at higher output voltage levels, and energy during magnet demagnetization is recovered to the power grid. Both platforms are designed as modular systems from a mechanical point of view, making them easily adaptable to the requirements of individual medical applications or experimental physics.
Current supplies from production of EVPÚ can operate in the range from 30 A to 2 500 A, power range from 400 W to 400 kW. Power supplies for the superconducting magnets are in the output current range from 100 A to 15 000 A, with power from 1 kW to 400 kW.
Each design is individually realized and the technical parameters of each power supply are discussed with clients at all stages of the development.