Historical research guide · 1154 · 1999
Power-generating electric motor
Yoshiaki Takahashi
In one minute
Yoshiaki Takahashi's 1999 United States patent is a brushless electric motor with two additions. First, each pole of the permanent-magnet rotor carries a flat, very strong magnet in a slot at its base, specified with a maximum energy product of at least 50 MGOe, preferably at least 100 MGOe, and built as two layers of different magnet alloys. Second, beside every field coil on the stator sits a separate induction coil that takes out electric power as each rotor pole sweeps past. The motor turns by switching: a Hall-effect sensor sees a rotor pole arrive, energises the next field coil so its core attracts the pole forward, and the current in the coil that has just done its work fades as the pole moves away. A capacitor across the induction coil can tune it to the frequency produced at low speed. The stated aim is a motor that keeps itself running from a starting input while storing power.
Connection
Chapter 2's energy-accounting section teaches how a device on a bench becomes evidence. A switched-coil motor with a generating winding is the cleanest possible example: its architecture is fully published, it is buildable with ordinary parts, and the only thing that decides what it does is a careful measurement of real electrical power in and out over a long, closed run with every store of energy accounted for.
From the source
The claimed machine. A power-generating electric motor comprising a rotor with at least two magnet poles, an armature coaxial with it across an air gap carrying field cores each with a field coil, a brushless control circuit, a high-energy-product permanent magnet inside each rotor magnet pole with a duplex structure of an inner Co–Fe–Y layer and an outer Fe–Nd–B layer, and an induction coil adjacent to each field coil for the generation of electric power.Claim 1; also claims 9 and 12
The magnet specification. The high-energy-product magnet has a maximum energy product of at least 50 MGOe, preferably at least 100 MGOe, and a permeance coefficient of 1.0 to 4.0, preferably 2.5 to 3.5; the embodiment used a magnet of 144.7 MGOe with a permeance coefficient of 3. A further such magnet may sit inside each stator field core.Claims 5 to 8 and 10; Detailed description; Preferred embodiment
How it turns. Hall elements, one per field coil, detect a passing rotor pole; each output drives a transistor that excites the next field coil so its core becomes a south pole attracting the rotor's north pole forward, while the excitation of the preceding coil dies away as the pole moves off. Repeating the sequence rotates the rotor without brushes, and each passing pole induces a current in the adjacent induction coil that is taken out as electric power.Detailed description, the operating sequence; Preferred embodiment, Figures 6 and 7
Tuning the generating coil. A capacitor, variable in the embodiment, connected in parallel with the induction coil tunes that circuit to the induction frequency at a low rotor speed, 500 to 800 revolutions per minute in the description and about 800 in Figure 9, so that power can be taken out effectively at low speed.Claim 11; Detailed description; Figures 8 and 9
The measurement that decides it. The patent states its objective as long self-running from a starting input with storage of electric power. What settles any such objective is the same for every machine: real input power and real output power measured with instruments that capture phase and waveform, over a run long enough that the state of charge of every battery, capacitor and magnet at the start and end is known, ideally with the loop closed so the machine runs on its own output.Summary of the invention, the stated object; the measurement standard is the site's
The way in
https://patents.google.com/patent/US5861693A/enHow to cite it
Yoshiaki Takahashi (1999) Power-generating electric motor US5861693A