Study On Cooling Process Of High Speed Brushless Doubly-fed Superconducting Generator

High-speed brushless doubly-fed superconducting generator in the field of ship electric propulsion has a very broad application prospects. In this paper, the development of HTS motor as the background, calculating the cryostat heat leakage, and the cooling process of high temperature superconducting motor and load loading process was studied.For cryostat, to determine the leakage quantity of heat is the precondition of the system safety and stable operation, thus correctly calculating the heat leakage on the system safe and stable operation is of great significance. Heat leakage of cryostat are introduced in this paper and the calculation method of determining the heat leakage of the system, and according to the low temperature cooling power of cold box, whether low temperature cold box can meet the cooling requirement of high temperature superconducting motor.High temperature superconducting motor cooling process is the high temperature superconducting motor from cooling at room temperature of 293 K to 67 K, in the process of cooling, divided into stages of open loop and closed loop, the state of low temperature from room temperature cooled to 67 K time is closely related to the inlet flow, in order to determine the best cooling scheme, provided by CFX software on cooling process of the numerical simulation on temperature field. By the open cycle simulation results it can be seen that the cooling time decrease with the increase of the inlet flow; Simulation results can be obtained by the closed cycle, within the scope of a certain flow, cooling time decrease with the increase of the inlet flow rate, flow increased to a certain value, the cooling time basically remain unchanged. After the comprehensive consideration of various factors, and puts forward the choice in the process of open cycle inlet flow rate of 9.5 L/min, select entry in the process of closed cycle cooling scheme of flow rate of 7.5 L/min.Load in the loading process of high temperature superconducting motor AC loss caused superconducting coil temperature rise, lead to high temperature superconducting coil near liquid nitrogen temperature, so numerical simulation load loading phase of the superconducting coil temperature field for the safe and stable operation of HTS motor is of great significance. Under a certain flow provided by CFX software numerical simulation, the relationship between the load and the highest temperature superconducting coil. At the same time, studying on load between 20 W to 40 W, the temperature does not exceed 77 K on the superconducting coil of the subcooled liquid nitrogen flow rate value, finally it is concluded that the relationship between the load and traffic, the rule for load flow control to provide the basis in the process of loading.