A design scheme for high voltage power supply system for accelerator

introduction

The power supply system supplies power to the accelerator, including a DC-200~-350kV 60mA main power supply, a 30kV 100mA power supply and a 10V 3A filament power supply, of which the 30kV power supply and the 10V power supply float on the high potential of a 350kV power supply. In order to reduce the interference of the power supply system to the power grid and other parts of the accelerator, the three-phase AC mains first passes through a 50kVA isolation transformer before supplying power to the power supply system. The electrical block diagram of the system is shown in Figure 1.

1 DC-200~-350kV main power supply

This power supply is an accelerator high-voltage power supply with high output voltage and high power. It consists of AC voltage stabilization, power inverter, high-voltage boost, control, detection, protection and other parts, as shown in Figure 2.

The key parts of the power supply are: 1. Power inversion; 2. High voltage part; 3. High voltage lead-out part (i.e. how to connect the output high voltage of the power supply to the accelerator).

1) Power Inversion

Since the power output power is relatively large (about 20 kilowatts), the power inverter part adopts a full-bridge inverter circuit, as shown in Figure 3.

Its power tube adopts intelligent high-power IGBT.

2) High voltage part

Since the output voltage of the power supply is as high as 350kV, the high voltage part uses two high voltage transformers, which are voltage doublers and rectifiers respectively, and then superimposed, as shown in Figure 4. The entire high voltage part is placed in an oil tank.

2 DC30kV, 100mA (-35kV potential) power supply

The power supply has an output power of 3 kW and requires an adjustable voltage of 10kV to 30kV. The key point is that the output voltage of the power supply is superimposed on a 350kV main power supply, which requires an isolation potential of -350kV. For this, the solution is: the three-phase AC power from the 50kVA isolation transformer is input to the high-voltage step-up transformer with an isolation potential of 3.50kV through a 5kVA voltage regulator (voltage adjustable), and then rectified and filtered to output 30kVDC 1OOmA (-350kV potential). As shown in the relevant part of Figure 1.

3 10V 3A (-350kV potential) filament power supply

Although the power supply has a small power, it also requires an adjustable output voltage. The key point is that the output voltage must also be superimposed on a 350kV main power supply, that is, the isolation potential must reach -350kV. The solution adopted is: the AC power from the 50kVA isolation transformer is input to the step-down transformer with an isolation potential of 350kV after passing through a 0.5kVA output voltage adjustable regulator, and then obtains AC10V 3A (-350kV potential) as shown in the relevant part of Figure 1.

4 Power system structure layout

According to the system configuration diagram shown in Figure 1, according to the size of the required volume of each part and the size of the standard cabinet: 50kVA voltage regulator is a cabinet; power conversion part is a cabinet; 50kVA three-phase isolation transformer and 5kVA voltage regulator and 0.5kVA voltage regulator are placed in a cabinet. There are three cabinets in total. The high-voltage transformer, high-frequency high-voltage rectification and high-power high-voltage resistor of a 350kV power supply; 350kV isolation boost transformer and rectification and filtering part of 30kV (-350kV potential) power supply, 350kV isolation transformer of 10V (-350kV potential) filament power supply, etc. are placed in one oil tank.

5 Conclusion

The high-voltage power supply system for accelerator is its key component. The design scheme proposed in this paper has practical guiding significance for the design and development of high-voltage power supply and high-potential power supply.