Three Phase Voltage Multiplier
Three Phase Voltage Multiplier
The Cockcroft-Walton turbine voltage multiplier
electric circuit | wind | generalWhether you make your own small DIY
wind turbine alternator or use a
stepper motor to generate elecricity, one common problem is that the generated voltage is too low to be used to charge a 12 Volt battery.
In our article
stepper motor voltage doubler circuit we present one way in which the voltage of
three phase AC electricity from a stepper motor can be increased at the same time as
rectifying the output into
DC electricity which
can be used to charge a battery.
In this article we will present a more advanced circuit which can take low voltage three-phase AC electricity inputs (of around 5 VAC) and rectify them into
pulses of 15V DC electricity which can be used to charge a 12V
lead acid battery. This circuit is perfect for use with
Sturmey-Archer Dynohubs and other 6 Volt
dynohubs which are commonly used in small DIY wind turbines powered by homemade
PVC wind turbine blades.
Cockcroft-Walton Turbine Voltage Multiplier
The image above shows the circuit diagram for the
Cockcroft-Walton three phase turbine voltage multiplier. Click on the image to view the original full size version. This circuit was designed to operate with a
1 Watt 5 Volt AC output three phase mini
horizontal axis wind turbine (HAWT).
Since a 12V battery needs at least 12.5-14 Volts DC charging voltage, the circuit is designed as a
voltage quadrupler. Because voltage is dropped in the diodes, the net result is a working
voltage tripler which converts 5 Volt RMS AC elecricity into pulses of around 15 Volts DC.
The diodes used in the circuit are standard
1N4001 diodes rated at 1 Amp current at up to 50 Volts. The
capacitors used should ideally be rated at 3x the peak output AC voltage of the turbine, however, since a 15V
zener diode is used to
clamp the maximum voltage, cheaper 16V-rated* capacitors could be used.
Excess power in the system (voltage spikes of over 15V) is dissipated by the
power zener diode. The zener used must have a power rating in excess of the absolute maximum power output of the turbine (e.g. a 2 Watt or 5 Watt power zener diode for a 1 Watt rated turbine).
*
It should be noted that 16V-rated capacitors could be destroyed if the power zener diode fails or is disconnected accidently.
The component labelled
OPT1 is an opto-isolator included to enable a computer to track when power is being sent to the batteries (and which can of course be omitted if not required). The LED (labelled
LED1) is used to give a visual indication of when current pulses are reaching the batteries, with the 4.7k resistor ensuring that the current available to the LED is very low so little power is wasted.
Instead of using individual
diodes, a pair of
bridge rectifiers can instead be used as shown in the photograph above.
Find out More
For more information about this three phase voltage multiplier and its usage with a micro wind turbine generator, click here to read about
London Home Wind Power Pilot Project on the excellent
Earth Notes website.
Article Last Modified: 09:22, 1st Oct 2007Comment on this Article
If you have any comments on this article, please email them to
neil@reuk.co.uk.
Recommended Related Articles
People who read this article also enjoyed the following articles:
Three Phase BasicsGet an understanding of three phase wiring in wind turbine alternators
Article Last Modified: 15:13, 19th Aug 2008wind | electric circuit | websitesStepper Motor BasicsLearn more about stepper motors and their use in RE electricity generation
Article Last Modified: 09:54, 4th Apr 2007wind | educationPermanent Magnet GeneratorBuild a wind or water power system with around a PM Generator
Article Last Modified: 11:44, 21st Jul 2008wind | hydroDIY 2kW Wind TurbineRead about a home built 2kW wind turbine constructed from scrap
Article Last Modified: 08:46, 4th Oct 2007wind | recyclingStar Delta Wiring CalculatorAn online calculator to work out the output voltage and current for an alternator wired in star or delta configuration
Article Last Modified: 13:39, 10th Mar 2008education | wind | electric circuitPVC Wind Turbine BladesLearn how to make your own PVC wind turbine blades
Article Last Modified: 15:16, 19th Aug 2008windElectricity with Stepper MotorsFind out the basics of generating electricity with stepper motors
Article Last Modified: 17:07, 10th Jun 2008windStepper Motor Voltage Doubler CircuitDouble the voltage from a stepper motor using two bridge rectifiers
Article Last Modified: 10:45, 9th May 2007general | electric circuit | educationHow I Built A Wind TurbineRead how a wind turbine was built for under US$150
Article Last Modified: 15:16, 19th Aug 2008wind | educationWind Turbine Axial Flux AlternatorsLearn more about the design of an axial flux alternator - used in wind turbines and hyrdo power
Article Last Modified: 09:27, 7th May 2008wind
|
|
|
