Here are two electric trikes I have developed: both of these bikes are powered by computer tape drive motors, the bigtrike(48volt) uses one motor via chain drive (with gears), the smalltrike uses 2 motors direct drive onto the rear wheels(36volt).(well in reality the small trike now uses a hub motor on the front wheel, see hubmotor section).

bigtrike------------------------------------------------------------------------smalltrike

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Some ongoing experiments I'm working on at the moment Last update: july 22nd, 2005

1. Small Petrol Generator to charge batteries for very long distance riding using hub motors for motive power.

Warrick Smith of Numurkah Secondary School in Victoria, Australia is using the magneto out of a TRX-350 three wheeler and hes getting 25amps at 24volt at 2,500rpm using a Honda whipper snipper 4 stroke motor (thats probably open circuit amps??i'm not sure on that one)
I've just set up a Briggs/Stratton 3hp four stroke on bigtrike. Think I will call the bigtrike the "Brius" (any resemblance to hybrid car names is purely coincidental (nudge, nudge, wink, wink).Briggs/Stratton has same diameter output shaft as tape drive motor (amatek brand), makes connecting them together simple.

I have tested a 40v tape drive motor but am getting better results with a 20v tape drive motor so have switched to the 20v amatek. With the 20v tape drive motor I use it to start the Briggs/Stratton (BS). Once the BS kicks over it makes the amatek spin faster than its normal operating speed and it becomes a generator. So by making a circuit with the 36v battery bank to the amatek it immediately begins acting as a motor and starts the BS and then the amatek becomes a generator when the BS fires. I am getting much better charging amps using a 20v amatek with a 36v battery bank. My first test was a 40v amatek with a 48v battery bank but needed high rpm to get good amps. The 24v amatek at idle is giving good amps into the 36v battery bank.
24v tape motor giving 50-70volts(open) near idle (managed to zap myself today!!!!) and 2-4amps charging current when connected to batteries at near idle speed. Open current not measured but should be around 20amps similar to 40v motor.Its charging much better than the 40v tape drive motor was. When charging 3 batts. batt. voltage is about 43v at idle. So gennie supplying maybe 150watts continuous to batts at idle (increasing BS speed increases amps and volts). Tried charging 24v battery bank but to much load as alot of amps are supplied. Seems to be ideal match a 20v amatek with 36v battery bank,
this was using wet cells (standard car batteries) will try sla-agm tomorrow (6 lots of 10ahr agm, 2 lots of 36v in parallel). Wired up the 6 AGM batteries. Very good results. The generator supplying 4amps at just above idle.

11th July, 05: Am now using 48v brushless motor on front wheel for driving. The controller for this motor has an undervoltage and overvoltage cut out. Unfortunately using a 48v battery bank with the gennie running gives over the voltage rating of the controller. So I'm using a 36v battery bank with the gennie on gives between 51 to 55volts depending on rpm of gennie (perfect voltage for the controller to operate). This means that when I turn off the gennie the brushless drive motor on the front wheel will cut itself off when battery voltage starts to drop. I will have to run on rear motor or restart gennie when battery voltage drops to low for front motor, the rear motor which is brushed and has no controller and will run on any voltage.I'm getting up to 20amps(suspect batteries were quite flat during this measurement)of current out of the gennie on a 36v battery pack. Thats alot of amps. I can vary amps by adjusting speed of petrol briggs/stratton motor. At idle its puting out about 6amps (perfecto!!!!!!!!!!!!!!!).Using jump starter agm batteries so have to be careful not to put too much current into them. Almost ready for some road tests,.... yeee haaaaa.

22nd July, 2005: Did a 14km road test, some steep hills some flat road. Petrol used was not measured as this was just to see if everything working ok. Next step is measuring petrol consumption. During test briggs/stratton was left running most of the time, amps into batteries varied from 5 to 10amps. During acceleration the petrol motor did go under more load (and slow slightly) and amps increased by about 2 or 3 amps compared with low driving motor loads (eg flat road running). Compensated by increasing rpm of petrol motor. The 20volt amatek motor being used as a generator got very hot but due to their robustness no damage was done, I will have to install a fan on the shaft to cool amatek motor (pics later when I sort that out). Top speed was 40km/hr on slight downhill incline, 30km/hr on flat road using front cpu front hub motor. Trike quite scary at 40km/hr is too fast for this machine, quite a few vibrations developed. Will be installing to brushed gearless hub motors to rear wheels in 3to4 weeks time, and will do away with front motor drive. Present rear wheel drive is very good for hill climbing but top speed on rear motor alone is 15km/hr (its geared very low). On arriving home and checking battery voltages after an hour to settle each battery of the 3 lots of 17ahr in series (36volt) gave 12.8, 12.8 and 12.75volts. This equates to fully charged state!!!!!
So after a 14km ride the batteries were fully charged on arriving home. This is a very good result indeed as it means range of trike will be limited only by amount of petrol which can be carried (have added 4 litre petrol container to trike).At this stage fuel consumption looks very low, the fuel tank was quite low when I left on the test ride (I had spare fuel on board just in case), I estimate there was less than 250ml of fuel in the tank (thats a guesstimate: probably between 150-250ml) giving 14km, that would equate(at worst) to about 60km per litre (but this has not been measured as yet, thats the next step after I put fan on generator to keep it cool.

some pics

2. Solar Cells to provide battery charging for long distance riding using hub motors for motive power.

I'm only using BS motor above as a temporary measure until cheap flexible solar cells become available.

I've done some testing of small solar cells from Dick Smith electronics. They are rated at 0.45v and 400mA. After testing have found they very stable at around 0.45volts it doesn't vary much, but the amps varies alot depending on anlge of sun, cloud etc. 350mA is about the maximum they produce. I've done a few sums and it turns out if want to charge a 48volt battery pack with 8 amps of current from the solar cells I would need an array which is 1metre wide by 7.5m long. Thats not very practical or encouraging BUT... after doing some basic calculations i've found that the efficiency of these cells is very low, about 3 to 4 % of the sunlight is converted to electricity. So it turns out that good quality cells running at about 12% efficiency would reduce this area needed by about 1/3. So instead of requiring an array 1m wide by 7.5m long, I would need an array 1m wide and only about 2.5m long. Now thats quite a reasonable length for my big trike .

Next problem is to find some cheap, efficient and lightweight solar cells. At the moment flexible/lightweight solar cells are far too expensive for me to get some. But there is a large factory in China tooling up to produce these cells and they have indicated they expect to be releasing the first cells later this year (2005). So hopefully if the price is right, I'll give it a go.

3. Converting a high voltage (350?VOLT) fisher/paykel washing machine motor ( a large brushless dc motor) to run on 24volt to 48volt D.C.

I've spent alot of time getting fisher-paykel washing machines motors to run on 24volt (original circuit was developed by Warwick Smith of Numurkah School, Victoria), I did eventually get it to work though it was very inefficient ( most likely due to the basic circuitry and partly because the fisher/paykel motor used ceramic magnets not neodymium).

I must say that is would be much much easier to use a pre-built controller to do this, I haven't tried with a normal controller as yet but as long as the hall sensor voltage is 5v on the fisher paykel motor it should work (I haven't tested the hall sensor voltage as yet) but there is really no reason to build your own controller as I have done. If you build the circuit below the motor will run quite inefficiently.

Have recieved a 48v brushless dc motor controller used on a hub motor in an electric moped. As time permits will try running the fp motor with it.
Basically as long as the fisher/paykel hall effect sensors located on the motor run at the same voltage as those in the hub motor which the controller is designed to run, it should work. Anyone know what voltage the hall effect sensors on the fp motor use??
Note: fp motor windings have to be reconfigured into parallel before using on low voltage dc, they are generally in series which gives a high resistance which suits the high voltage power supplied when used in a washing machine.

How to rewire into parallel:

Basic circuit to run fp on 24volt (original circuit designed by Warwick Smith, Numurkah Secondary College, Victoria
Note: L1, L2 and L3 are leds.(they flash on/off in sink with hall sensor firings, rather pretty I must say).

Stator windings only shown, rotor containing magnets removed. Motor is rewired into parallel, you can just make out lots of white electrical tape and some wires in centre portion of fp motor. Have used this setup to run electric trike but have found the circuit it not very efficient. Will be trying some pwm controllers built for electric hub motors in near future.

4.Deconstructing the CSIRO high efficiency motor (reverse engineering I guess) 

The CSIRO in australia have developed a quite amazing motor suitable for use on electric vehicles. Its was developed and is used in solar powered racing vehicles. Its extremely lightweight and very powerful. Anyway just for my own interest though I might have a bit of a 'crack' at reverse engineering how the motor works from information gathered from the internet. I cant use any of the CSIRO pictures or information on my website, so have drawn a few pics that i'll add here over time. The CSIRO website can be found by doing a google search entering " tip csiro machines success "

On the their website they say that anyone is free to use the information to design their own motor. So to design a motor would require understanding how their motor works, so here goes. A very in depth thesis on this type of motor can be found in "Modelling and optimisation of a permanent magnet machine in a flywheel" by Stanley Robert HOLM.

Just a few pics to start with. On their website they show high resolution pictures of the windings and magnetic rotor (an axial flux type motor). Its possible from the picture of the windings to deconstruct the winding pattern for each phase, the wires are colour coded on the high res picture so no problem to zoom in a work out how the windings are done. Each phase ( a 3-phase motor) has two windings associated with it, below is the winding pattern for one phase (yellow and orange wires). Basically the yellow and orange are separate windings which mirror each other on each side of the dividing disc (the windings are done around some sort of disc, no idea what material it is made of, its a bit hard to make out the width/depth of the disc they are wound around but appears to have some depth to it.....maybe a 4 or 5 mm (guesstimate)).

Overlaying these two pictures gives how the windings appear on the high res pic of the actual windings on csiro website.
(one csiro movie on the web shows a rotor and magnet array in which the winding ends have been tidied up somewhat from the pics I've been working from.)


The magnet array has 40 poles (sort of!!!), it uses a halbach array but for simplicity will just say that each lot of 4 magnet segments is one pole (north or south), will go into halbach array later. Picture below shows one pole (4 magnet segments), I've drawn this picture to scale as the dimensions of the magnets compared to the width of the wires would be rather important. So for each width of 4 magnets there are 6 wires making up the same width.  (postscript: if we consider each  pole as being made of 4 segments in a halbach array as shown by numbers 1 to 4 below, then for each pair of wires (for example the two red wires) when one wire is in the centre of one magnet segment the other wire will be sitting on the join between two segments (roughly), not sure if that will have any relevance for making the motor run. Or could it be that by having the wires in pairs the magnetic field strength in between the wires is more concentrated, will explain a bit later)



Picture below shows wiring pattern for 3 poles, note only top wires (on this plan view) could be shown, wires also connect on bottom but only have shown two red connections for bottom wires for clarity (all the other colours connect similarly).




next step figuring out how current flowing through wires interacts with magnetic field in hall bach array.
to be continued................
The reason I'm going right back to basics here is to help myself to understand how the motor operates, if it can shed light on it for any other interested persons then very nice. There could very well be some errors in my attempt to understand the motor but here goes anyway.

Imagine you have two magnets (strong ones!) you have opposite poles of each magnet facing each other and you try to push the magnets together, as you do that it becomes very hard to push them together as they are repelling each other, the closer they get the harder it becomes to push them together. The magnetic field lines become squashed together tightly and the magnetic flux density becomes high. This is basically whats happening in the pictures below, the magnets are pushed together with opposite poles facing each other. In the small gap between the magnets are the windings.
So what we really have is copper wire passing through a very strong magnetic field. When current is passed through a wire there is a magnetic field generated around the wire, its this magnetic field around the wire which interacts with the magnetic field from the magnets which the wire is sitting in.
 The picture below shows the most basic situation having  two permanent magnetic poles and a wire carrying a current passing between them.
The plan view shows the magnetic field lines going from a south to a north pole ( I think thats the convention)
[errata: convention seems to be arrows go from north to south so picture below purple lines should have arrows pointing the other way, but green arrows for direction of movement I think are ok]
. The small picture inserted in the right hand bottom corner shows this plan view in 3d (sort of). The other small 3d image (right hand top) shows what happens when the poles are reversed.
Basically what it shows is that the direction the wire will want to move in (green arrow) will be the same direction if the current direction is reversed as the wire moves from one pole to the next pole. ( brushed motors do this switching using brushes, the csiro motor uses 3 hall sensors to achieve the switching of current direction i.e. a brushless motor). There is a rule of physics called the 'right hand rule' which is used to determine the direction the wire will want to move in according to direction of magnetic field lines and direction of current flow.



If the picture above is shown with two alternating poles adjacent to each other it can be seen easily how switching of the current is needed to keep the wire moving in the given direction (as shown in the picture below). Reversing the current flow from that shown in the picture would make the wire move in the opposite direction.

Ok so thats the basics of how movement is achieved. It should be possible to use this basic principle with the drawings I've done above which show how the csiro motor windings are arranged to further understand how this motor works.......well thats the theory lets see what happens.
Might be appropriate time to introduce the halbach arrangement of magnets and how that complicates the simple principle above.
Basically the halbach array is an arrangement of magnetic poles which by its nature concentrates the magnetic field more on one side of the magnetic disc than the other side (alot more in fact, one side gets almost all of the magnetic field and the other side gets hardly any at all. So by further concentrating the field in the space where the windings are sitting the magnetic field becomes even stronger and the torque of the motor increased). I'm guessing this means since the fields are concentrated on the side of the magnetic disc where the wires are located that it makes the motor more efficient also. Also it means there is no need for an iron backing plate to concentrate the magnetic field and so the motor weight can be reduced substantially.  There is a simple experiment I came across somewhere on the net that uses the halbach array to make a fridge magnet which on one side will stick to the fridge but when turned on the other side it wont stick to the fridge (no idea what the link is to that page), demonstrating how the field is concentrated on one side of the magnetic disc. A google search using 'halbach array' will give plenty of info on it.
Somewhere the csiro had mentioned that they had to cut magnets at the correct angles and position on the magnetic plate (non-iron I think) so that the fields would follow the halbach array design. This cutting of the magnets allows the angle which the magnetic field is in relation to the wire to be varied (to give a type of halbach array) and gives a sinusoidal varying magnetic field, which apparently is a rather good thing.

One other thing worth mentioning is that brushless motors use two phases with power on at one time, the reason for this I'm not sure. But the third phase can be used to monitor the back emf and give some information about torque ( I think the force or torque of the motor is proportion to the back emf, so for example if your going uphill the torque or load in this case is high and so back emf which can be monitored via the unused phase will be high, but I dont think any use of back emf will be necessary to make the motor run ,fortunately!). So the switching of the phases becomes quite a complex pattern, two phases on and one off at any given time, also the phases are constantly being switched on and off as the motor rotates. But fortunately knowing the correct positions of the hall sensors (really spacing between the hall sensors) is given on csiro website. Usually controllers use a 30degree or a 60degree spacing for hall sensors (or was it 60degress and 120degrees???bad memory here), both types of controller are readily available as chinese hub motors can use both types of hall sensor positioning. So finding a controller to match should be no problem.

The thing I dont understand as yet is there are two sets of windings per phase in the csiro motor and if the current should be flowing in the same or opposite directions for each winding of one phase but I think can be solved by looking at the simple magnetic arrangement is previous two pictures above.

 The picture below shows basically one magnet on top row (divided into 4 parts) and one magnet on bottom row (divided into 4 parts), the grey region is the central core around which the windings are wound. The magnets are stuck to a backing plate. The windings are shown coloured.
Phase 1 windings are shown in red and purple, phase 2 in blue and phase 3 in yellow and orange. The windings and core will all move as one unit and the magnets remain stationary.

 

 Removing phase 2 and phase 3 wires, just looking at phase one wires it can be seen that for them to want to move in the same direction if the current is flowing in the same direction in the purple and red wires. (the windings are paired on each side of the core). So that is good news (if I'm correct I was worried that the red might have to flow in one direction and the purple in the opposite direction which would make controlling the flow complex. But since the current flows in the same direction for both the red and purple windings it should be simple to connect both coloured wires to the controller).

 

The csiro motor uses a hallbach array at 30degrees, which has the effect of concentrating almost all of the magnetic field lines on the side of the backing plate where the coils are located. So instead of using an iron backing plate to concentrate the field lines the magnets themselves act to concentrate the field lines, since an iron backing plate is not needed the weight of the motor can be reduced. The picture below shows how the field lines are arranged which is produced by cutting the magnets at certain angles to adjust the north/south alignment in relation to the windings.



The picture below I have removed all the windings except for one red windings and one purple winding ( i.e. I have removed one of the pairs of wires for each colour). The picture shows the force acting on the wire as it moves through the magnetic field from left to right, so in 4 different positions.

Using the right hand rule it can be seen how the force on the windings varies in a sinusoidal manner (shown with green arrows). So only at the middle of the magnet array will the force be perpendicular to the front face of the magnets (the large green arrows which show direction of rotation of the windings and core unit).


Once the red and purple wires move out of this set of magnets into the next set of 4 (not shown) then the direction of current flowing through the wires must be reversed to continue the movement in the same direction. I think that is achieved by the hall sensors.

A hall sensor in a motor works by turning on/off as a north and south pole pass by it, so might have to try and work out if a standard hall sensor would be turned on/off by the hallbach array in same manner as a standard magnet array i.e. will a north south pole be passing by the hall sensors or because the field is varying sinusoidally will some different type of hall sensor be required

Wire used in the motor is called Litz wire which has many strands of fine wire ( one csiro media release quoted the number of strands as about 400),
the diameter of the wire can be roughly worked out from the pictures on csiro website as follows:
Measuring diameter of inner side of magnet array gives about 233mm diameter, at that point the wires are very close together and looks like each wire each touching each other (on the outer circumference of the magnets the windings have some gap between them). There are 120 wires around the circumference of the motor so the circumference where the wires are touching each other is about 732.3mm, dividing by 120 gives a width of 6.1mm. So my guess would be the litz wire is about 6mm in diameter and maybe 400 strands.

Litz wire makes motor more efficient by reducing eddie current losses in windings.

Magnet dimensions: 
There are 160 magnets on a disc (40 poles in hall bach array). Magnets are in shape of a trapezium and seem to fit very neatly together with no spaces between magnets. Dividing outer circumference by 160 equals 6.19mm. Dividing inner circumference by 160 gives 4.58mm.
Outer diameter (315) minus inner diamter (233mm) and divide by 2 gives radial width of magnets = 41mm.
So working from the csiro website pics I get magnet dimensions of:
 outer width = 6.19mm, inner width = 4.58mm and height about 41mm.
Picture below shows working:



Picture below shows magnet dimensions and a smaller picture of one magnet to scale.
  drawn to scale>>


CURRENT PROJECT ( begun in October 06)

SOLAR RECUMBENT 
The Plan: build a functional solar powered electric vehicle. Looks like the trike and motor/batteries will come together in a reasonably short amount of time. The solar panels will be a bit difficult. I was planning on using flexible solar panels which would be safer than normal silicon glass type in case of an accident. But the best efficiency I can get at reasonable cost in flexible solar panels is about 6%.  Going with higher efficiency cells would mean using silicon wafer type which may be quite dangerous in an accident with shards of wafer glass a possibility. Plan is to use an x5 motor on 72volts if the trike can handle the speed but will see what happens with that.

It will be a very simple design (no grand plan on this one), the trike is shown below, the solar panels will form a simple roof, and perhaps a very basic clear thin perspex fairing on the front. Thats about it. Connecting solar panels to batteries I'll get some help to use a simple maximum power point tracker to maximise the  solar cells output ( I think that will be the most time consuming and hardest part of the project is to match the solar roof to the batteries, whichever voltage I land up using, perhaps two sets of batteries, one for charging and one for motor power, will start with sla agm batteries, lithiums would be too expensive for me to use them at the moment.........maybe down the track a bit).

Was very fortunate to get a slingshot trike built in usa about 20years ago ( is perhaps only one in australia as the owner had it shipped out to Australia when he moved here from the usa) .  Has been sitting under his house for that time hardly used, was in not so good condition just due to its age, thanks to Steve from Newcastle for parting with his slingshot and letting me bring it back to life.
This will be quite a long term project but things are moving along quite well.

Heres a few pics:
I've stripped everything off the trike and given a few coats of paint and some clear enamel to help resist scratches and chips to the paint a bit.



Below after painting. Just put some garden hose on the frame as a temporary seat. Front wheels were 20" but was only a few cm road clearance so have put some 26" wheel on front. Rear wheel is presently 24" but will be 26" or 27" when I install the hub motor.



Where I'm up to below: trike is in working order. Next is to install motor and batteries and quite a few other fiddly bits to do on it (such as front disc brakes etc etc) .

Update: solar recumbent project 010808
Progress has been extremely slow on the slingshot trike, have added front and rear suspension and a front fairing. Some initial test rides using x5303 motor on 48v 25amp controller ( before fairing added) were very successful. The trike suspension works extremely well on rough roads gives for a very smooth ride.
The max speed on ashphalt road with 25amp 48v controller was on a slightdownhill slope 53km/hr and the trike was very stable at that speed. No signs of any problems with steering etc. Am just now wiring up for 86volt 35amp testing as shown in pics below.
Below showing the slingshot trike at my outdoor workshop at Pokolbin Hunter Valley, taking a break admiring the view.

Rear view of modified slingshot trike.Batteries not in place as yet just three lots of 24v 15ahr in series for testing wiring connetions are correct. Battery pack will
be 86v 60ahr in total made from cobalt oxide packs. Each pack is 24v 15ahr and were packs initially used in cyclone bikes from taiwan, the packs had a reputation for catching fire, but the fires seemed to be related to poor bms management systems. With decent care the packs are proving to be quite safe ( fingers crossed).
Supension on rear is from an old motorbike the rear swinging section being from an old mountain bike.

Front fairing and windscreen ( perspex) are from an electric three wheeler project from a girls high school in south australia. Which I've done a bit of cut and paste to fit onto the slingshot trike.

Front suspension is using motor bike front struts with some additional frame to accomodate them. The system is very simple and works well, over the longer term
there is the possibilty of wear of the struts and becoming loose being an issue, but I cant see that occuring for some time. Original steering system of slingshot trike
still being used with some minor additions to strengthen somewhat.

Controller is V2 crystalyte digital with irf4110 mosfets ( 12 lots ) 100v capacitors. Put into a smaller size case. Controller has regen braking and forward/reverse built in. Two torque arms used on the x5303 motor, along with 4 lots of torque washers ( 2 inside frame, 2 on outside of frame).

Lighting system for night is 4 lots of cree P4 leds, led system made by Kerry of Ktroniks.Gives equivalent of a car headlight illumination but using a fraction
of the current.

Should be doing some testing on 86v 35amp in the next couple of weeks. Braking system currently only have caliper on rear and relying on regen brake, need to add disc to front at some stage.

(I'll update as I go along with this project)

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