The Dmic Permanent Magnet Brushless Dc Motor Field Weakening Expansion Speed

A brushless motor, as its name suggests, is a motor without brushes, slip rings or mechanical commutator. The burshless DC motor is essentially configured as a permanent magnet rotating past a set of current-carrying conductors. In this respect it is equivalent to an inverted DC commutator motor.Commonly, a brushless DC motor is composed of an inverter, shaft sensor and a pure synchronous machine of which the back-EMF is usually trapezoidal.There are different configurations and applications of brushless motors, such as record players, VCR players, drive fans, blowers, electrical tools, electric vehicle and so on.When especially used in electric vehicle, it is hoped to have a wide speed range. But the magnetic field for PM motors is hard to be weakened, which therefore arises many researchers' interests nowadays.In this dissertation, a new control method of BLDCM is presented in order to get a wide speed range. The simulation models of the two control systems are built with Matlab/Simulink. From the simulation result, it' s easy to find the advantage of this new method.And experiment based on the new control method is conducted. Both the simulation analysis and experiment all show that this method is better than traditional method without any changing of the motor rotor.