MK1 single phase low RPM electric generator

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MK-1 Low RPM Single Phase DC Generator

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MK-1

Low RPM Single Phase DC Generator

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14030901

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SANJAY DOCTOR

MIKROFIELDS RESEARCH UNIT 131, Silver Beach Apts., Suryavanshi Hall Lane, Off Savarkar Marg, MUMBAI 400028.

Phone: 9892000857. Email:[email protected]

Website: http://sites.google.com/site/mikrofields

MK1 – Low RPM Single Phase DC Generator

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[1]

MK1 is a stand-alone Low RPM generator

producing 3-phase AC current. It is rectified to

supply single phase DC. Shown here in test at the

workbench driven by an electric motor.


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[2]

Both sides of the generator have 12 stator coils in a radial layout. They are

wired in 3 groups to provide 3 phase AC current. Colour coding is done in

Red, Blue and Yellow. Black coiled wires connect corresponding stator coil set

on each disc to complete the circuit.


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[3]

Strontium ferrite magnets provide a strong magnetic field to allow current

generation at low RPM.

Cut into 32 wedges, they rotate between the stator coils. As they rotate,

the strong magnetic field creates a current in each set.

12 wires bring the AC current into the

rectifier panel where each current is

rectified through a rectifier bridge. The

positive (red) and the negative (black)

are grouped respectively to produce the

single-phase DC supply.


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[4]

MK1

Technical Overview

The Generator is based on the design of Alfred T. Forbes, engineer and

inventor, in New Zealand. Improvisation and modifications were made to

create the first prototype model – MK1.

It is a low rpm, low voltage, 3-phase permanent magnet alternator with

internal rectifier diodes to supply direct current.

The design objective was to create a low RPM generator. Renewable energy

applications like wind, water turbines and steam engines have speeds in the

100 – 800 RPM range. Commercial alternators have speeds above 2000 RPM.

Coupling these together requires expensive high ratio gearing or a maze of

belts and pulleys, which are not energy efficient and require high

maintenance.

Strontium Ferrite Magnets are placed in 32 wedges on a rotating disc (rotor)

made of industrial grade electro-mechanical laminate. The power of these

magnets is greater than conventional metal magnets. The ‘long throw’

capability allows for larger air gaps and with higher construction tolerance

enabling an amateur craftsman to assemble the generator.

12 sets of stator coils are placed radially on either side of the rotor. The

north-south direction of magnetism in each magnet is opposite to the ones

next to it. As the rotor turns, the stator coils are caused to be magnetised

first in one direction and then in the other. This generates alternating

electricity as the rotor turns.

The stator coils are grouped into 3 phases (of 4 coils each). At any point,

only 4 pairs of the coils are being covered with 4 magnets while the

remaining 8 magnets are just passing away or coming to the stator coils. This

eliminates the ‘clogging effect’, which would immobilise the magnets and

make it impossible to start again.

The output of each coil is separately passed through rectifier diodes to

produce a DC output, which are then connected in parallel to produce the

final supply.

Team:

Sanjay Doctor.................Design Manager

(Late) KG Kodolikar........Engineer

Shivsagar Singh ..............Technician

Development phase: 1999 – 2009.


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[5]

Production

The MK1 can be manufactured in an workshop with basic tools and a

workbench. It is our aim that the production take place in a rural setting and

that a group of artisans trained as technicians. A cluster of cottage

industries and home industries with a Service Centre as a hub can create an

ecosystem to create an assembly line, which works in a batch-processing

mode.

Casting, lathe operations and industrial coating are the only capital and skill

intensive process which can be outsourced within the ecosystem to specialist

workshops. However in a later evolution, the lathe operations should be in-

house to save costs and develop in-house skills for other production lines.

It is also possible that a technical school function with the unit to create

opportunities for the marginalised, like poor youth, the landless and women,

to learn technical skills and take their rightful place in a rapidly industrialised

rural economy.

Applications

The dynamo can be used with any motive power unit, which works at low

RPM. Biogas engines, biomass gasifiers, wind and water turbines are all

possible sources.

It is proposed that the compressed biogas be used to drive an engine

coupled to the dynamo.

1. Use of a small HP engine requiring less fuel at any point of time

2. Use of catalytic convertors in the exhaust to reduce CO emissions.

Power is produced just-in-time rather than stored in expensive battery

systems. A pressurised Biogas holding tank would store the gas supplied in a

steady stream. The charge controller would distribute power to the actual

load and send the surplus power to the battery bank system used as a

backup.

The rated power

output of the

dynamo as per

original design are:

Rated output (Watts) Volts (DC) Amperes (DC) RPM (at rated output)

1008 36 28 740

896 32 28 673

784 28 28 597

672 24 28 523

560 20 28 450

448 16 28 376

392 14 28 338

336 12 28 301

(Source: Alfred Forbes, Inventor)


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[6]

MIKRO

!!The philosophy of ‘Mikro’ has evolved from the ideology of Gandhian thought.

It calls for the empowerment of the human being through technology which

works at a micro level of the household to allow value added production to

meet the basic and aspirational needs of the family.!Inspired by ‘Unto the Last’, it calls for freedom of the household from

monolithic centralised means of production, empowerment to choose the

technology of choice based on the local environment and a bias for the local

economy.

Mikrofields stands for principles of independence and freedom, accessible technology for the homestead,

and decentralised stand-alone micro power production.

Sanjay Doctor, founder and inventor of MIKROFIELDS RESEARCH UNIT has

been pursuing his interest in sustainable development since 1994. He co-

founded with his wife, Architect Harita, SAT Research and Consultancy (P)

Ltd to pursue applied research and development in organic farming,

ecological housing and appropriate technology. They toured rural India

extensively, training farmers in biodynamic farming and rural technologies.

The company was dissolved in 2003. Subsequently MRU has been founded in

2008 to pursue the ‘Mikro’ agenda.

Above: Ho Chi Minh Cycle trailer

Left: Water flowforms

Below: Biodynamic Agriculture

Planting Calendar


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[7]

QUADRANT A

NATURE

1 Biodiversity

2 Agriculture

QUADRANT B

BUILT ENVIRONMENT

3 Shelter

4 Water and Sanitation

5 Energy

QUADRANT C

KNOWLEDGE

6 Education

7 Livelihoods

8 Health

QUADRANT D

SOCIAL INTERFACE

9 Culture

10 Gaia

THE DEVELOPMENT MATRIX

Based on the research of the past decade, a holistic integrated framework for

planning and program execution is offered for developmental work. At a

macro-level it divides the framework into 4 quadrants with a total of 10

streams.

LEVEL DESCRIPTORS

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FUTURE RESEARCH AND DEVELOPMENT

1. Control Panel for Home Solar PV

system using Phase Width

Modulation (PWM) charging.

2. Development of under 100W

stand-alone electric generators

for micro windmills with vertical

axis blades.

Inspiration: Aeroturbine by Dr Bill Becker

3. Biogas plant with external

rotating drum and pressurised

storage silo.

MK1 single phase low RPM electric generator

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