Brushless dc motor controller can be divided into commutator motor controller of brushless dc motor controller of two categories. Dc motor controller on the structure, price and maintenance performance than ac motor controller, but long drive control ac motor controller problem has not been satisfactorily solved, thus the motor controller with good control performance has been widely used. At present, although the speed of ac motor controller control problem has been solved, but because people need for the modification of the casting equipment and a long process. The speed control of ac motor controller is not popular, dc motor controller system is still in wide use. Dc motor speed control system is to use a constant dc voltage controller of dc motor power supply, first of all, by changing the resistance in the armature circuit implementation speed. This method is simple, easy to implement, easy manufacturing, low cost, but the disadvantage is that the efficiency is low, mechanical properties is soft, can't get a wide and smooth speed regulation performance. This method is only applicable to small power and variable speed range without occasion. The control method can obtain a wide speed range, low speed rate and smooth speed regulation performance. But the main drawback of the method is that the system has a large weight, large area, low efficiency, maintenance difficulties. In recent years, along with the rapid development of power electronic technology, by the thyristor inverter power supply controller of dc motor speed control system is composed of motor generator controller replacement, speed performance is far beyond the generator controller and motor speed control system. Especially the large scale integrated circuit technology and the rapid development of computer technology, the precision of speed regulation system of dc motor controller, dynamic performance and reliability have greatly improved. High power devices such as the development of power electronic technology is replacing the thyristor, one of the better performance of dc speed regulating system.
