High torque brushless DC motors and generators

• US 20040108789A1
• Filed: 12/09/2002
• Published: 06/10/2004
• Est. Priority Date: 12/09/2002
• Status: Abandoned Application

• Current Assignee: Eric Giles Marshall
• Original Assignee: Eric Giles Marshall
• Inventors: Marshall, Eric Giles
• Application Number:
  US10/313,889
• Publication Number:
  US 20040108789A1
• Time in Patent Office: Days
• US Class Current: 310/216
• CPC Class Codes: H02K 1/24 Rotor cores with salient poles ; Variable reluctance rotors
• CPC Class Codes: H02K 1/2733 Annular magnets
• CPC Class Codes: H02K 1/276 Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM]
• CPC Class Codes: H02K 1/2773 consisting of tangentially magnetized radial magnets
• CPC Class Codes: H02K 2201/06 Magnetic cores, or permanent magnets characterised by their skew
• CPC Class Codes: H02P 2209/07 Trapezoidal waveform
• CPC Class Codes: H02P 6/16 Circuit arrangements for detecting position

Abstract

This invention relates to geometric, electrical, and electronic techniques improving torque, power, cost, size, weight, reliability, and efficiency of electric generators and motors using the following: Geometric relationships eliminating lateral magnetic short circuits, providing sine wave output waveforms, and allowing axial extendibility; Radial and axial Permanent Magnet concentration; Speed independent rotating transformer inductive coupling; Precise speed independent rotor position sensing using a threshold and comparator circuit to provide Hall Effect low speed & Back-EMF medium to high speed sensing; Bi-directional Buck-Boost PWM converter topology using H-bridge power transistors, parallel reverse diodes and an H-bridge connected inductor.

Claims

1. A combination of fundamental geometric relationships between the rotor and stator magnetic poles in an electric motor or generator that eliminates lateral magnetic short circuits, and provides axial extendibility, and induces a sine waveform in the main windings;

where;

the lateral distance between adjacent magnetic poles in the rotor is sufficiently greater than the pole segment width in the stator to eliminate lateral magnetic short circuits, and

the magnetic poles are axially extendable either by an axially stackable claw structure or by axial slots, and

a sine waveform is induced in the main windings by a trapezoidal, parallelogram, skew, helix, arc, or other non-rectangular geometric relationship between the rotor and stator poles.

2. A fundamental geometric relationship between the rotor and stator magnetic poles providing a Magnetic Flux concentration proportional to the surface area of Permanent Magnets coupled to rotor pole pieces versus the surface area of the rotor pole pieces that interact with the stator;

where;

the rotor poles are formed by axial slots or claw structure, and

the concentration is a combination of the radial and axial surface area of the Permanent Magnet coupling.

3. A brushless, speed independent, rotating inductive coupler providing regulating control of rotor voltage and current;

containing;

an electronic chopper, and

a rotating non-contact AC transformer, and

a rotor mounted electronic rectifier.

4. A pulse width modulation (PWM) circuit topology providing continuously variable bi-directional Buck-Boost electrical current and voltage control and matching;

where;

an H-bridge is formed by four power transistors and parallel reverse free-wheeling diodes that control electrical currents in a bridge-connected power inductor, and

Buck PWM controllers provide upper H-bridge bi-directional transistor switching and opposite H-Bridge lower diode conduction, and

Boost PWM controllers provide lower H-bridge bi-directional transistor switching and opposite H-bridge upper diode conduction.

5. A precise and variable speed rotor position sensing provided by a threshold and comparator circuit that switches between electromechanical sensing and Back-EMF sensing;

where;

Electromechanical sensors provide low speed sensing, and

Back-EMF comparators provide medium to high speed sensing.