US 7,888,904 B2 · Virtual moving air gap for an axial flux permanent magnet motor with dual stators

Abstract

An axial flux electric motor comprising a rotor and a first and second stator. The first and second stators have a first and second air gap located between the first and second stators and the rotor, respectively, and the second air gap is greater than the first gap. In one embodiment, the coils of the first stator and the coils of the second stator are in parallel. The motor further comprises switches which alternatingly energize the coils of the first stator and of the second stator based upon required torque and required speed of the motor. In a second embodiment, the coils of the first stator and the coils of the second stator are in series and the motor further comprises switches which selectively bypass the coils of the second stator in order to reduce the back EMF of the motor and increase the maximum speed of the motor at a given input voltage.

Claims17

Dependent claims

An axial flux electric motor and control comprising:

a rotor having a plurality of magnets mounted thereto;
a first stator displaced from said rotor by a first air gap, said first stator having a plurality of slots defined therein, the slots wound with electrical wiring to generate a magnetic field when the wiring is energized with current;
a second stator displaced by a second air gap on an opposite side of said rotor from the first stator, said second stator having a plurality of slots defined therein, the slots further wound with electrical wiring to generate a magnetic field when the wiring is energized with current;
a motor control adapted to regulate a flow of power to the first and second stator wirings using high-frequency pulse width modulated inversely proportional duty cycles whereby said motor has a first torque, operational speed, and BEMF value when driven solely by said first stator, and whereby said motor has a second torque, operational speed, and BEMF value when driven solely by said second stator;
wherein said first and second stators are electrically wired in a parallel configuration;
and
wherein the first stator has a greater duty cycle during low speed operation of the motor and the second stator has a greater duty cycle when the motor is operating at a relatively higher speed.

4 more elements

An axial flux electric motor and control comprising:

a rotor having a plurality of magnets mounted thereto;
a first stator displaced from said rotor by a first air gap, said first stator having a plurality of slots defined therein, the slots wound with electrical wiring to generate a magnetic field when the wiring is energized with current;
a second stator displaced by a second air gap on an opposite side of said rotor from the first stator, said second stator having a plurality of slots defined therein, the slots further wound with electrical wiring to generate a magnetic field when the wiring is energized with current;
a motor control adapted to regulate a flow of power to the first and second stator wirings using high-frequency pulse width modulated inversely proportional duty cycles whereby said motor has a first torque, operational speed, and BEMF value when driven solely by said first stator, and whereby said motor has a second torque, operational speed, and BEMF value when driven solely by said second stator;
wherein said first and second stators are electrically wired in a series configuration;
and
wherein said motor control is further adapted to direct said flow of power to bypass said second stator to maintain a selected BEMF value at an increased motor operational speed.

4 more elements

Dependencies are inferred from the claim text.

Virtual moving air gap for an axial flux permanent magnet motor with dual stators

Life of this patent

Virtual moving air gap for an axial flux permanent magnet motor with dual stators

Life of this patent

Abstract

Claims17