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Parallel Path Magnetic Technology (PPMT) is an advanced magnetic force control technology that is applicable to motors, rotary actuators, linear actuators, magnetic latches, and generators. PPMT uses permanent magnets controlled with a field coil in parallel magnetic circuits. PPMT is a revolutionary concept that has been demonstrated in a wide variety of devices. Flynn Research Inc. is the patent holder on basic and specific PPMT patents.
Compared to conventional electromagnetic technology PPMT devices are:
All PPMT devices use two or more permanent magnets placed in parallel with steering coils between the magnets. We will illustrate PPMT basics in the form of a simple magnetic latching actuator:
The basic magnetic circuit consists of a flux steering coil on each flux path as shown in figure 1. If there is no current in the coils the magnetic circuit then acts as if the coils do not exist.
Figure 1. Basic PPMT actuator (flux steering coils off)
However if current flows in the flux steering coils to produce a magnetic polarity, as shown in figure 2, the magnetic flux produced by the coils couples with the permanent magnetís flux and the result is four units of force at one pole of the device (four units, not two, is due to the squared force law of the combined permanent magnet flux). Once the flux has switched and the actuation elements have moved to create an air gap on the zero force side, the steering coils can be turned off and the actuator or motor will remain in this new state at four units of permanent force with no power required. A momentary coil pulse with the opposite polarity, will switch the actuator in the opposite direction.
2. Basic PPMT actuator steering coils engaged to switch all magnetic flux
to one actuator pole
In the actuation of the PPMT device, the steering coil only needs to have sufficient current to equal the flux of one permanent magnet. Thus, in PPMT devices a given amount of magnetic flux can be controlled with only half the field coil power required by conventional devices. Furthermore, the force generated by the PPMT device will continue, with no power required, as long as the geometric arrangement of the elements allow for it.
This same basic magnification of the mechanical/magnetic/electric coupling relationship exists for generators and motors in a similar manner as it does for the actuator used in this simple example. Compared to an equivalent conventional motor/generator, or actuator a PPMT device has: Higher power density, Higher power efficiency, Lighter weight, Smaller physical size, Wider torque zone with high efficiency, Wider power zone with high efficiency, and Cooler operating temperatures. Figure 3. Shows a simplied cross section of one type of PPMT rotary motor.
Figure 3. PPMT motor cross section
Click here to download a pdf file (350k) with details of PPMT physics for rotary motors and generators.