The analysis and experimental research of the second-generation EAST active feedback power supply

To achieve the maximum current rising rate and obtain a high precision, the second-generation EAST active feedback power supply applies voltage mode while retaining current tracking mode of the first-generation power supply. In voltage mode, power supply outputs an average voltage linear to the reference signal. When high output voltage is applied to the load inductance, output current increases approximate linearly. Over-current protection is activated to turn off the power transistors once increasing current exceeds a certain threshold. The power stored within the load inductance will be released through the inverse parallel diodes of the IGBTs to DC side, which leads to rising of the voltage on DC side and it becomes easier to cause over-voltage protection. So current limiting protection is triggered after over-current protection to maintain the permissible maximum output current. Experimental results prove that voltage mode can greatly improve the ability to suppress vertical unstable displacement of plasma in Tokamak device.