Linear Electric Machines

Linear motion is richly present in various industries, from direct electric propulsion in urban and interurban people movers on wheels or on magnetic "cushions" (MAGLEVs) to indoor transport of goods (conveyors, etc.), through plunger solenoids (to open hotel doors and as electromagnetic power switches), to compressor drives by linear oscillatory permanent magnet (PM) motors, smart phones integrated microphone and loudspeakers, and controlled vehicles suspension, etc. Besides the traditional rotary motor drives with mechanical transmissions, which mean friction limitations (weather dependent) in traction (heavy vehicles), more losses, positioning errors (backlash) in the process, and higher maintenance costs to handle them, linear motion in industry by direct electromagnetic forces is free of friction limitations for traction, free of mechanical transmission, and thus more efficient, with less maintenance cost and fewer positioning errors (backlash). This explains why they are used in so many applications already since the dramatic advancement of power electronics and digital control in the last four decades.

Modeling, performance, design, control, and testing of linear electric machines (LEMs) show notable differences with respect to rotary electric motor drives, which warrant a dedicated treatment of these aspects.

The Second Edition (First Edition: 2013) concentrates on the above technical aspects of various types of LEMs in close relationship with specific applications via numerical examples of modeling, design, control, and testing, with ample representative results from literature, industry and some of the authors contributions, such as:

• Technical field and circuit modeling of linear induction motors in flat configurations for low and high speeds (with and without dynamic end effects) and in tubular configurations short travel design, control and testing

• Linear synchronous motor (LSM) drives in dc-excited, homopolar, reluctance and superconducting excitation configurations for urban and interurban high-speed vehicles propulsion and integrated propulsion and levitation (in MAGLEVs) modeling, design and control with full-scale numerical examples, with emphasis on lower KWh/passenger/Km at high speeds

• Flat and tubular linear permanent magnet (PM) synchronous motors (L-PMSMs), mainly destined to industrial indoor transport for automation at high efficiency in clean rooms

• Linear "flux-modulation" motors-- new breed, suitable for very low-speed applications due to higher thrust density

• Plunger solenoids in various applications including new valve PM actuators with millisecond response time

• Linear resonant PM oscillatory motors design, control and testing mainly destined to compressors for higher efficiency in compact drives

• Attraction and repulsive force suspension (levitation) systems for MAGLEVs

• Active and passive guideway MAGLEVs in urban and superhigh-speed interurban transport at lower Kwh per passenger/km (in lighter vehicles without wheels)

The numerous numerical design and control examples (with practical specifications) throughout the 23 chapters of the book allow the reader deep and fast access to a practical but thorough unitary (good for comparisons) methodology in designing and controlling LEMs for various applications.