Research On Practical Issues For AC Motor Drives

As the continuous development of power electronics technology, computer technology, and AC motor control technology, the role of AC motor drives in the field of modern industry has been more and more important. However, the reliability of drives has affected the stability of a motor control system, especially the vulnerability of power devices which often leads to a series of motor control system malfunctions.This dissertation aims at AC motor drives’ practical problems, and to design a high-power AC motor drive considering performance, cost and reliability. Firstly, the dissertation describes the purpose and significance of AC motor drives, emphases the importance of drives’reliability and stability. Then, a power circuit of the AC motor drive is designed, including switch drive module, signal detection module, protection module and isolated power module.In order to verify the reliability of each circuit module in the AC motor drive, a series of related experiments for each circuit module have been carried out. When designing the AC motor drive board, layout principles and thermal management principles are strictly followed, to ensure the signal integrity and good temperature characteristics. The switch drive experiment verifies the fast respond speed of switch drive circuit. Through measurement of outputs of the secondary power supply, it’s ensured that each output voltage and ripple voltage of the isolated power supply are controlled in the acceptable range. Finally, a brushless DC motor control system is designed. Combined with software module design concept, it’s realized that current and voltage is real-time monitored, and the brushless DC motor is controlled by speed closed loop.