NOVEL WIDE-RANGE SPEED CONTROL OF PERMANENT-MAGNET BRUSHLESS MOTOR-DRIVES

This paper presents a novel approach for wide range speed control of p ermanent magnet (PM) brushless motor drive, including both sinewave an d squarewave versions, As compared with conventional flux-weakening co ntrol, the approach takes definite advantages that it can be applied t o the squarewave PM brushless motor drive directly, and even to the mo tor drive with negligible mutual inductances between phase windings. M oreover, it is easier to implement than flux-weakening control because no coordinate transformation is needed, The key of this approach is t o make use of the transformer EMF in such a way that it weakens the ro tational EMF when the motor operates above the base speed, leading to achieve constant-power operation. Computer simulation and experimental results show that the proposed approach works well.