Research Of Low Harmonic Power In High Power-density Electric-drive System

High power-density electric-drive system used in wind tunnel propeller model is researched in this dissertation with the background of the key technology development of rebuilding items. The system is composed of four parts, high power-density motor, low harmonic variable-frequency power, spray oil cooling with high temperature and pressure and the online test of the dynamic parameters. The research in this thesis is focused on the low harmonic variable-frequency power for the system meeting the needs of wind tunnel propeller model testing requirements.The effects of harmonic on high power-density asynchronous machines are analyzed, specially the calculation methods of harmonic loss. The SPWM with low harmonic is designed aiming at the characteristics of calorific severity and high rated power-input of motor in the system, to satisfy the special qualification of variable-frequency power. Aiming at the rotate speed regulating requests of propeller the high efficiency control strategy is researched to increase the power density of motor.Then the armature current method is investigated, which is proposed by no-load and full-load tests to calculate the efficiency and power factor of the motor, being extended to the rare-earth permanent magnet synchronous machines. The proposed method has been experimentally tested, which is found to work as theoretical expectation and used to oil fields saving energy.Finally the ripple of torques is simulated by Matlab. Through modeling variable-frequency power, the method of specified harmonic-restrained is simulated. The simulation results show that the harmonic content is reduced and the power density is increased.