WHAT IS BEING PROPOSED IS THE DEVELOPMENT OF PERMANENT MAGNET BRUSHLESS DC MOTORS USING NEODYMIUM BORON IRON AS THEPERMANENT MAGNET MATERIAL.

WHAT IS BEING PROPOSED IS THE DEVELOPMENT OF PERMANENT MAGNET BRUSHLESS DC MOTORS USING NEODYMIUM BORON IRON AS THEPERMANENT MAGNET MATERIAL. THIS MATERIAL, NEWLY INTRODUCED AT THE MMM CONFERENCE IN PITTSBURGH ON NOVEMBER 10, 1983, SEEMS TO HOLD THE POTENTIAL FOR SIZE WEIGHT REDUCTIONS FOR A GIVEN LEVEL OF OUTPUT OVER ANY OTHER PM MATERIAL CURRENTLYAVAILABLE INCLUDING RARE EARTH COBALT MAGNETS AND AT A LOWERCOST. MAGNETIC CIRCUIT MATERIAL REDUCTIONS OF 50% BELOW TH THOSE ACHIEVABLE WITH SMCO5 APPEAR POSSIBLE. THERE ARE HOW EVER DRAWBACKS, PARTICULARLY REGARDING LOSS OF COERCIVITY WITH INCREASING TEMPERATURE, WITH A RESULTING DECREASE IN ENERGY PRODUCT (BHMAX). OF EVEN GREATER IMPORTANCE WOULD BE RAPIDLY INCREASING SUSCEPTIBILITY TO DEMAGNETIZATION DUE TO CROSS FIELD MMF. MEANS OF THERMALLY INSULATING THE ROTATING PERMANENT MAGNET STRUCTURE IN ORDER TO MINIMIZE THEDEGRADATION OF ITS OUTSTANDING PROPERTIES ARE PART OF THIS PROPOSAL.