《《Interior Permanent-Magnet Synchronous Motors for Adjustable-Speed Drives》.pdf

738 IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. IA-22, NO. 4, JULY/AUGUST 1986 Interior Permanent-Magnet Synchronous Motors for Adjustable-Speed Drives THOMAS M. JAHNS, MEMBER, IEEE, GERALD B. KLIMAN, SENIOR MEMBER, IEEE, AND THOMAS W. NEUMANN Abstract-Interior permanent-magnet (IPM) synchronous motors air gap. These motors, referred to here as surface PM possess special features for adjustable-speed operation which distinguish synchronous motors, are also known as brushless dc motors, them from other classes of ac machines. They are robust high power- inside-out motors, electronically commutated motors, as well density machines capable of operating at high motor and inverter efficiencies over wide speed ranges, including considerable ranges of as by a wide variety of manufacturer-specific trade names. constant-power operation. The magnet cost is minimized by the low This range of terminology obscures the fact that, in most magnet weight requirements of the IPMdesign. The impact of the buried- cases, they are variations of the same class of machines. magnet configuration on the motors electromagnetic characteristics is Several interesting characteristics arise when the permanent discussed. The rotor magnetic circuit saliency preferentially increases the magnets are mounted inside the steel rotor core. A sample quadrature-axis inductance and introduces a reluctance torque term into the IPM motors torque equation. The electrical excitation requirements geometry for this type of machine, known as the interior for the IPM synchronous motor are also discussed. The control of the permanent magnet (IPM) synchronous motor, is shown in Fig. sinusoidal phase currents in magnitude and phase angle with respect to 1. Although this may at