Radial Flux Technology (RFT) Generator Design and Development History 3 kW GMI GENERATOR.

Radial Flux TechnologyRadial Flux Technology (RFT)(RFT)

Generator Design and Development History

3 kW GMI GENERATOR

GMI Technology BackgroundGMI Technology Background

Global Motors Invent Pty Ltd was established in 1995 to design and commercialize a new technology for electric motors and generators with higher efficiency, lower weight and more compact dimensions than any other available in the world.

The 2 technologies developed were the T Flux based on ultra low weight with no steel content in the design and Radial Flux Dual Stator using more conventional manufacturing methods and materials.

The design basis of this technology objective was a radical approach to magnet and winding configuration which led first to the design of the T Flux Technology (U.S Patent 5798591 1998)

T Flux TechnologyT Flux Technology• The T-Flux motor design

achieved a 10% gain in electrical efficiency while reducing weight and materials by 85%. The dramatic size reduction of the model T-Flux 406 against a typical 4 kW 3phase motor can be seen below.

The Radical design pushed all the relevant technologies for motors and generators to the limit: it has no steel at all. The uniquely configured windings were held with a custom designed plastic shell containing the permanent magnet ring and windings. This is illustrated below

This concept was executed in a number of prototypes, one of which is shown in the following photographs where the section has been halved

A second smaller model was produced

as is seen to the right. The larger (cut

open) model produced 8 kW and the smaller model 4

kW

A less serious but functional application was a powered bicycle

Trial applications included a water

pump to illustrate the

significant size reduction for comparable

output

This technology breakthrough become the design basis for a range of motors used in Solar Racing Car and Boat

design from 1995 to 2000, winning 43 awards in this period.

After these trial products the chosen production versions were focused exclusively on the supply of motors to the

Solar Race car industry where the extreme weight reduction and performance gains were of greatest value.

The Shell® car here

incorporated T Flux

motors

Comparison of T-Flux 406 Motor and Typical 5 hp, 3,000 rpm, 3 Ph

MotorT-Flux 5 hp Comment re T-Flux

Input @ Full Load 4.025 kW 4.8 kW almost 800 W less input

Output @ Full Load 3.686 kW 4.0 kW

Full Load Speed 2,651 rpm 2.892 rpm

Full Load Torque 13.77 nm 13.00 nm

Full Load Efficiency 91.58% 83.33% 8.24% higher efficiency

50% F.L. Efficiency 94.4% 81.0% 13.4% “ at lower load

Power Factor Full Load 99.0% 85.0% 14.0% higher pwr factor

Power Factor 50% F.L. 99.0% 76.0% 23.0% “ at lower load

Weight 7.5 kg 47 kg only 1/7th the weight

Start Torque 230 nm 33 nm nearly 7x the torque

Torque at 35 KVA 110 nm 42 nm nearly 3x the torque

KVA at 42nm 12.9 kVA 35 kVA 64% less power needed

Motor Outside Diameter 200 mm 240 mm 1/6th smaller diameter

Motor Length 100 mm 300 mm 2/3rds shorter

Volume of motor 3,145 cc 13,586 cc 75% size reduction

The T-Flux has a linear torque speed relationship and speed voltage relationship giving improvements to ease of control. It can be wound to run at any speed and robust rotor construction enabling speed to 10,000 rpm

Radial Flux Dual Stator Radial Flux Dual Stator TechnologyTechnology

• The T-Flux design was so afar ahead of its time in features such as all plastic components, zero steel content and resulting potential for some electromagnetic interference with electronic devices in close proximity that funds for further development and commercialization were not readily available despite its success in the solar car and boat applications.

• The specialized tooling required for the winding and injection molding process was a further restraining factor for investors.

As a result the inventor of the T-Flux and driver of the GMI Technology, Paul Lillington, developed an entirely new approach to achieve many of the efficiency, size and weight advantages of the T-Flux design without any of its possible application constraints.

The new design is based on the same radical rethinking of the magnet and winding configurations possible except this time with conventionally available materials and manufacturing technology. (Radial Flux PCT Patent 2008903100)

Radial Flux Dual Stator Radial Flux Dual Stator TechnologyTechnology

It is, simply expressed, a generator within a generator, giving in one compact configuration the output of 2 generators.

This was achieved through a rigorous conformance to 3 design rules:

•Minimum iron•Minimum magnet material•Maximum active copper

The Radial FluxRadial Flux Concept

Conclusion

The radial flux concept is based on

successful technology with a proven track record, and the prototypes are being custom designed to meet the unique challenges of a wind turbine.