Schematic diagram of the thyristor high current test. Because the anode power supply of the thyristor is obtained from the factory power reduction, the frequency is, the anode voltage is low, and the power dissipation of the thyristor components on and off is very small at this time, and it can be ignored. Ignoring the effects of power dissipation during turn-on and turn-off, the power dissipation of the thyristor can be approximated as the power dissipation P of the on-state. The above formula for power dissipation of the thyristor is simplified as: The three-phase full-controlled thyristor rectifier is used as the test object. The main device parameters are as follows: the thyristor is ABB5STP28L4200, and the radiator is a clean and clean aluminum profile radiator. According to the product manual of ABB5STP28L4200, check the parameter table to get V. Adjust the wind speed of 8.2m / s below the radiator to be tested, and control the output current of the thyristor rectifier to 600A. After the temperature stabilizes, measure the shell temperature at 29.1 ℃ and the inlet wind temperature at the radiator below 24.9 ℃.
Substitute V200A into the average power dissipation in the on-state of the thyristor to obtain P and then the temperature T of the thyristor shell, the inlet air temperature T under the radiator, the power dissipated by the thyristor P and the thermal resistance of the thyristor radiator: you can find the output current of the R control thyristor 600A remains unchanged, adjust different wind speeds under the radiator to be measured, measure the temperature of the thyristor shell and the inlet wind temperature after the temperature is stable, calculate the thermal resistance value under the wind speed at this time according to the above calculation method, and plot the thermal resistance value under each wind speed as . Data analysis of the effect of wind speed changes on thermal resistance can be seen from Figure 3, the smaller the wind speed, the slower the heat dissipation of the radiator, and the greater the thermal resistance. The effect of the change in wind speed on the heat dissipation of the radiator is significant, each time the wind speed decreases 1m / s, the thermal resistance will increase significantly. Considering that the heat resistance of the heat sink is related to the fin, base, fin length, fin thickness, number of fins, base thickness, base width, shape, size, installation method, etc. of the heat sink, in order to explain the above The thermal resistance test data is limited by the small output current of the thyristor and the large heat capacity of the radiator. Increase the output current of the thyristor to 1000A and test the data again, and plot it together with the data at 600A.
