Research And Realization Of The Power Supply System For The Dynamic Resonant Magnetic Perturbation Coils On The J-TEXT Tokamak

MHD instabilities can affect the plasma confinement in the tokamak and the safety operation of the deivce. Using the active control coils to generate the perturbation magnetic field is one of the main methods to control the MHD instabilities at present. In order to do the research about the control of tearing modes instability by externally applied perturbation magnetic field, the dynamic resonant magnetic perturbations (DRMP) system has been developed on the J-TEXT tokamak. Power supply system is the essential component of the DRMP system. It provides exciting current for the DRMP coils, and directly affects the magnitude, configuration and mode spectrum of the magnetic field generated by the coils.The DRMP coils have some spectial requirements for the supply currents in terms of waveform, amplitude, frequency and so on. The coils are intended to operating at the DC mode and AC mode respectively. At the DC mode, the power system should provide two channels of DC currents with controlled amplitude and direction, the maximum amplitude of the current is up to10kA, and the current waveform could be set arbitrarily. At AC mode, the power system should provide two channels of sinusoidal currents with controllable phase difference, the AC current frequency can be adjusted in the bandwidth of1-6kHz, and the current amplitude must be up to5kA at5kHz frequency point. These special requirements not only limit the choice of the power supply topology and switching devices, but also raise strict demands on the power control system.According to the parameter characteristic and power supply requriements of the DRMP coils, the circuit topology and control system of the power system are developed. An overall power supply system scheme with separated DC and AC power units is proposed for the DRMP coils. Based on the analysis of the relationship between the output current ripple of the thyristors rectifier and the phase-controlled angle and value of the filter inductor, two thyristors three-phase full bridges in anti-parallel are chosen for the circuit topology of the DC power supply units. The parameters of the DC power supply units are designed. Characteristic analysis of the voltage series resonant inverter is carried out with both time-domain and frequency-domain method. The topology of the AC power supply units is presented based on the series resonant inverter with H-bridge using IGBT. Then, the parameters of the AC power supply units are also figured out. The control system of the designed power supply must comply with the standards of the J-TEXT CODAC system. The real-time control system for the DC and AC power supply units are designed based on the industrial personal computer and QNX RTOS.Research and design of the feedback control of the phase difference between the output medium-frequency currents of the AC power supply units are carried out. The current phase difference can affect the configuration and mode spectrum of the perturbation magnetic field. The study finds that the load difference between the two AC units has effect on the accuracy of the current phase difference control. The effect can be ignored with feedback control of the current phase of each unit. This method can also increase the flexibility of the the adjusting of the current phase diffefence. The phase-locked loop (PLL) technology is applied to the design of the phase feedback control scheme. A novel all digital PLL is proposed. Based on the proposed PLL, the design of inverter controller is completed. The controller can automatically realize the accurate feedback control of the output current phase according to the amplitude of the output current. The modeling and analysis of the proposed PLL is done, and the guides for the design of the parameters of the PLL are provided.Testing results of the hardware and software of the developed power supply system are agreed with the design expectation. The power supply system can meet with the power requirements of the DRMP coils quite well. It has been operating in the practical application. The operation performance is very wel. With this power system, J-TEXT has obtained abundant results in the aspects of driveling magnetic island rotation, unlocking the locked magnetic island, and the other related physical researches. The system is going to play an important role in the real-time feedback control of the tearing mode.