Significance, Development, Replication
Robert Adams of New Zealand is credited with the invention and development
of the motor that bears his name around 1969. The complete formal description
is: High Voltage Pulsed DC Permanent Magnet Switched Reluctance Electric
Motor. The term Switched or Variable Reluctance first appeared, curiously,
also in 1969 in a paper by Nasar in IEE Proceedings. Credit for the first
reluctance motor goes to Davidson's electric locomotive in 1838. Stepper
motors used in ink-jet printers, floppy drives, and robotics are common
examples of switched reluctance motors that achieve high performance,
continuous torque operation by using closed-loop magnetics but without
Principle of Operation
In the case of the Adams motor, permanent magnets are used in the rotor
to avoid the need for commutators rendering it in effect a brushless DC
motor. Its operation is explained in various and sometimes conflicting
ways. Most describe both a positive torque induced by the magnetic attraction
produced between the approaching rotor magnet and the passive ferromagnetic
stator core followed immediately by a negative torque produced by the
repulsive magnetic field that appears as the stator coil is energized
just as the rotor magnet and stator core reach opposition.
Adams increases performance further by taking
advantage of the collapsing magnetic field and capturing the induced back-EMF
current in the stator coil. This is performed by the second battery in
the diagram above (BAT2) which is charged by the back-EMF as it is routed
through rectifier D1, but which also prevents discharge of BAT2 back through
the coil windings. This two battery design would require periodic swapping
of the batteries.
The story behind the Adams motor is full of intrigue, conspiracy, and
amazing claims, like so many other "free energy" devices, that
feature superlatives ("the first working free energy device placed
in the public domain") and alien-sounding expressions like "time
reversed negative current" and "over-unity performance."
Many builders report "cold current"
effects when the motor is properly "tuned." The switching transistor
and drive coil wires are said to become cool or even cold to the touch.
With such distractions aside--for the moment--there is enough credible
documentation and evidence in existence to raise enough interest for a
considerable number of exerpimenters to actually attempt and reportedly
succeed in replicating this simple yet curious device.