Study And Optimization Of New EAST Fast Control Power Supply System

EAST superconducting Tokamak,a National Mage-project of Science Research of China,is a very important fusion experiment facility.The ability of magnetic confinement to plasma can be improved by elongating plasma cross-section to form divertor configuration in EAST.But elongated plasma has vertical displacement instability,plasma will move along the same direction when plasma equilibrium is out of control because of some perturb.Without control,plasma will dash against wall of vacuum vessel and disrupt,that will cause failure of plasma discharge.It is necessary to add the feedback coil in a vacuum chamber and supply it with a large power supply to suppress the vertical unstable displacement of the plasma.Therefore,it is necessary to develop EAST fast control power supply with excellent control performance.With the continuous development of EAST experiment,the demand for fast control power supply is also improving.The fast control power supply(pure analog control circuit)has been unable to meet the high demand for the power supply.It is necessary to upgrade the old EAST fast control power supply to the new EAST fast control power supply(digital control circuit)to meet the current situation.The new EAST fast control power supply is better than the old EAST fast control power supply in the output voltage,output current and response time and other parameters.The main work of this article is:(1)The structure of new EAST fast control power supply is introduced.Three single-phase H bridges are cascaded to form a branch.And the same six branches are connected in parallel through parallel shunt reactor to form the circuit topology of 18 H bridges.The modulation method of carrier phase shifted PWM and the voltage and current law of cascaded H bridge are deduced in detail.(2)The current control strategy of new EAST fast control power supply is introduced.The current control strategy of new EAST fast control power supply is introduced.The current mode control method is applied to make the power output current tracking the given signal and reach the dynamic and static requirement.The characteristic of new EAST fast control power supply is the high power and fast response.The power of new fast control power supply has been greatly improved.In order to make the output current response of new fast control power supply faster,this paper also proposes a voltage mode control method.The average output voltage of the H bridge has a linear relationship with the given signal.The constant high output voltage from the H bridge is directly applied to the two ends of the load coil to greatly increase the load current rising rate and accelerate the response speed of the output current.It can't realize closed loop feedback tracking and can only realize open loop control.So when using voltage mode control method,we need to change the given signal in a short time and apply current limiting control to prevent overcurrent protection.(3)The hardware circuit design of new EAST fast control power supply is introduced,including the design of the branch controller and the design of the total controller.And the simulation and experimental verification of the current mode and voltage mode are also introduced.