Research On Key Technologies Of Power Supply Control System For Three-phase Asynchronous Motor Type Testing

Frequency control technology is the core technology of high-speed rail,trains,subways and other public transportation.Besides,in the field of clean energy,variable frequency motor has an irreplaceable position.The frequency conversion motor type test is a necessary step for the inspection of new motor products.It can provide the test basis for product improvement.Therefore,the type test of the motor has an important position in the motor industry.Due to its scientific value,economic value and the important contribution made in the field of energy conservation the type test has become an important direction for domestic and foreign research institutions and companies to research and develop.First of all,this thesis analyzes the main components of the three-phase inverter power supply including inverter main circuit,filter circuit,data acquisition board,and data control board.The data acquisition board collects the voltage,current and other signals in the load to the control board.The control board controls the IGBT switching devices in the main circuit of the inverter through specific control methods.The main circuit of the inverter reverses the input direct current into a three-phase alternating current with harmonic components through the on-off of the IGBT switching device,and the three-phase alternating current is output to the motor after the filter circuit.Secondly,this thesis analyzes the use of the Eh-star method to measure the additional stray losses in the motor type test,because the use of auxiliary resistance will bring negative effects to the test,including the difficulty caused by the selection of the auxiliary resistance,the operation difficulties caused by the input resistance of the auxiliary resistance,the floating of the auxiliary resistance and the influence of the accuracy of the test result.For the influence of the auxiliary resistance,a new power control strategy is proposed in this thesis.The control strategy can provide the three-phase unbalanced current required by the Eh-star method for the tested motor without using the auxiliary resistance and verify the control algorithm.Finally,in order to implement this control strategy in the project,an 8-channel data acquisition board was designed.The data acquisition board uses Altera's EPM1270 G model FPGA as the core control chip for the input voltage,output current,and IGBT of the three-phase inverter circuit.The operating temperature of the device is subjected to data acquisition.The data acquisition board filters the collected signal through the optical fiber and transmits it to the next-level control board to implement the previously mentioned power supply control strategy.