increasing speed by switching phases rather than higher voltages ?

[John-uk]

Am I on the wrong track here but wouldn't it be possible to increase RPM of the motor by jumping a phase or two once the motor had reached or nearly reached the maximum switching rate of the controller. IE coil 1,2,3,4,5,6 etc on acceleration then 1,3,5,7 to give a higher speed. Or have I missed an obvious technical problem.

John UK

[Leslie]

Yes there are some Youtube clips and information on Delta WYE conversion and switching techniques.

Here is a good starting point.

http://www.youtube.com/watch?v=TAaTO67zWfw

http://www.youtube.com/watch?v=CrhRg9OrILg

Hehehe.

Warp drive huh? To boldly blow motors and controllers no man has blown.

[John-uk]

LOL. Excellent. Thanks very much for the prompt reply.I am going to have to try this. Im suprised that Goldenmotor don't build phase switching technology into one of their controllers it seems the obvious way forwards ? They have been doing it in heavy industry for years.

Regards

John UK

[muzza.au]

Any instuctions on how to build it?

[Leslie]

I'm not feeling too well ATM. So I might sit back a little on putting too much effort into this thread ATM, but I will do my best.

It requires you to undo the hub and de-solder the phase wires that meet to make the wye.

On my motor the end points are soldered together for WYE, insulated and indicated with a red arrow below.  



All phase ends then must lead to relays which can be housed inside the motor, then the relays all need to be supplied a switching current.

For WYE

3 DPDT need to switch the end points of the phase together and 3 starting points to the controller into WYE

For DELTA

The relay is activated, the 6 phase end and start points switch together in series into Delta triangle and the controller phase wires at the beginning of each series phase.

Its a matter of where you switch the phase endpoints, either together or to the beginning of each phase to make a series connection, and thus the controller wires can remain as is.

I will latter do a circuit diagram with coils, relays and switch power indicated when I feel more up to it .




No former rewind is necessary and nothing out of the ordinary needs to be addressed when dealing with both HALL sensor controllers or sensorless controllers.  It just works.

I haven't even attempted this but it seems that on lower voltages the back EMF from the motor may fall well within the fets capability.

Whether of not TVS's and resistors over the fet bridge is essential may be dominated by the type of fet used in the controller and this is not in my scope of experience, so do this at your own risk.

For some time Ive known that electric trains use this type of phase switching to give the motor high power on take offs and high speed once good momentum has been achieved but don't quote me on this.

This practice of delta wye switching is only something that I uncovered in some google searches when attempting to rewind a motor.

Google can give up a lot of information on the subject or Doctorbass over at ES might give some great advice..

[Mabman]

Thanks for the explanation 317537 and hope you feel better soon. I guess my only question is when will Golden Motor apply this? You would have to think that their competitors probably are

If I understand this correctly it seems that a 36V system with the switch and have close to the same top end as a 48v system which would mean less battery weight and cost. It obviously works and although it can be used as Dr.Bass does for very high speed I would prefer a setup that favors low end torque but has the switch to get up to a decent speed that is not way beyond the legal limits.

[Leslie]

How this works is by switching the motor phases from 2 in series or two parallel and one in series (WYE), into a single phase or two phases still in a single phase.depending on sensor triggering

DELTA mode lowers the inductance and impedances of each phase by half and draws more current from the controller by means of low resistance. Half inductance also stops current from converting into torque thus allowing higher voltages over each winding.

EG. In the single phase event. Say In WYE you have 34 windings in wye configuration, in delta you would have 17 windings. Each winding works as a voltage divider.  So in essence in delta mode your winding divide the supply voltages by 17 while in WYE the supply voltages are divided by 34.

This means with a 50v supply voltage in delta  mode  each winding will have approx 2.9v over each winding

While in WYE mode each winding would have approx 1.47v over each winding.  

Edited:

Where the speed comes into DELTA is the voltages applied over the 17 slots dictates that each slot (coil) voltage is twice as high and the magnetic field produced is higher from each slot (coil).

Where the WYE mode torque comes from is, the coil string 34 slots long and utilises more pole magnets and torque is milked from efficiency.  

Delta mode will by my observation draw more average current and lower the efficiency by some degree, so this is why a Delta/WYE switch over is preferable to maintain some efficiency over all..

[Leslie]

Thanks for the explanation 317537 and hope you feel better soon. I guess my only question is when will Golden Motor apply this? You would have to think that their competitors probably are

If I understand this correctly it seems that a 36V system with the switch and have close to the same top end as a 48v system which would mean less battery weight and cost. It obviously works and although it can be used as Dr.Bass does for very high speed I would prefer a setup that favors low end torque but has the switch to get up to a decent speed that is not way beyond the legal limits.

It is a question of legality reliability and efficiency.  You cant squeeze more distance out of a Delta configuration you just chew up more power.

You may need a bigger battery to get where you normally get too in which why not go for a higher voltage or a more powerful motor and just use a throttle..

Convenience would dictate practicality IMO.  If you were going for a short ride and carried no load a delta configuration would be a nice option to have.

Comming home with a trailer full of shopping, delta would no doubt heat your motor up needlessly.

Practicality is up to the end user and for most this is not a necessary pursuit.  A more powefull motor would probably be a better choice unless in Doctorbass's case you already have top of the line motor and want more.

Sure! If you want more, the MP is up to the task and is top of the line GM ebike motor just asking for some Delta mode love, but I would do my homework on the controller.

Edit:

At least with this Delta mod you do not have to mod your controller to take a higher pack voltage to get a better top speed.

[Leslie]

Iron core trans(former) rule of thumb for max efficiency states 6 winding turns per 1.2v.

So on a phase that divides the voltage to 2.9v per former, 14 turns is advised at least.  This figure is just under double of what is in standard motors we buy. Many motors have around 7~8~9 turns around each motor coil.

 
So a very light bike that needs not to stop and start all the time may be doable.



This is IMO why in electric trains the train has to be going a good speed before they switch to the faster phase setting.  Train motors are more than likely wound to be most efficient in between both phase configurations.

[John-uk]

I was thinking more like fooling the controller by switching the hall sensors. so at low speeds we use all three phases. IE 1,2,3, 1,2,3, 1,2,3, etc. Then once a predetermined speed is reached disable the hall sensors in sequence IE disable Hall sensor 1 and the motor would only power up coils 2 and 3. Disable hall sensor 2 and the motor would only power up coils 3 and 1. thinking about it on a 4 phase system you would only have to disable two opposing phases and you got exactly what you want without any hastle. Im wondering if they use 3 phases cos its a throw back to power generation. I will look into this there  has to be a way. OR NOT lol.

[Leslie]

I was thinking more like fooling the controller by switching the hall sensors. so at low speeds we use all three phases. IE 1,2,3, 1,2,3, 1,2,3, etc. Then once a predetermined speed is reached disable the hall sensors in sequence IE disable Hall sensor 1 and the motor would only power up coils 2 and 3. Disable hall sensor 2 and the motor would only power up coils 3 and 1. thinking about it on a 4 phase system you would only have to disable two opposing phases and you got exactly what you want without any hastle. Im wondering if they use 3 phases cos its a throw back to power generation. I will look into this there  has to be a way. OR NOT lol.

Three phase motors have been around for sometime in AC applications 3 phases DC motors are a little newish.

You can do DELTA WYE switching and I have seen these guys ride these bikes.  The efficiency shifts right up to higher RPM in DELTA.  An issue would lie in switching from delta to wye while going max speed.

The three phase has no ground other than each other.  The coil wire is insulated and there are only three wires that lead into the hub so at least one of them behaves as a ground.

You cant control hall sensors, they control your controller, though some ability to electronic time their behaviour would be awesome. This requires to physically advance the hall sensors and add a modulated an electronic digital delay to the signals.

Possibly look at getting a ground wire onto where all three phases meet into the WYE could bring the need to have higher voltages down by half.

High voltages are OK I guess hmmm, but to avoid long strings of cells is probably not a bad idea, less cells to go bad. 

Sure run your bike at 36v and have it able to switch to delta, 36v will be more efficient than 48v.

Instead of 48 or I'm thinking with my rewind I'm going to make a fast 24v motor by using thicker coil wire and 4 turns on each former..    Or even 12v with 2 turns per coil former.   WOW a 4 cell battery to worry about and the ability to use most components on the market at high efficiency.

[John-uk]

Hi 317517. I have been racking my brain as to how to do this. But most of the ways of doing it involve starting out from scratch with the motor or a complete redesign of the controller. As it happens I have a friend who works in the IT deparment of an electrical vehicle RD company and although he wont explain to me any of the technology they are researching he has said that " we are in the steam age of electric vehicles" and they are testing a controller that tunes your motor as is runs Quote " like the electronics on a combustion engine". I think we are on the right track with auto switching phases and or sensors but I recon we would need a small company to design an build it... AH well ................I wonder what would happen if .............LOL

[Leslie]

It would be nice to have the resources to try the numerous ideas thrown out by the world that  "wonders what would happen if".

You know you could power a large vehicle on the logic circuit out of a simple ebike controller and pair it up with some large 600v IGTB'S.  Use the new ESU's rumoured to change the world.  You only need two gears out of a cars transmission on a good motor.

The net weight of EV cars will drop considerably once we get an energy storage unit "ESU" that behaves like a gas tank, rather than, weighs like a Sherman tank.

Honestly the concept of gearless engineering attracts me so much more than its geared counterpart and crafty electronics can do this better and lighter.

Sure we are in the steam age of E-vehicles but the steam age from any perspective isnt that far off where we are now.

ICE is very inefficient and electric motors are extremely efficient.  Air coil axial motors are as good as 95% efficient and can use the innovation of sensorless technology.   People can make these colis around their hand.

New research is being conducted around iron powdered coils so that larger coils can keep all induction within the motor to find sweet spots and minimise iron losses.  Compared to current ICE technology, electric motors are far more simplistic its just that we cant see electricity the same, and the secrets on how to achieve practical applications around electronic engineering is at present more difficult to uncover.

As oil becomes more a impractical pursuit, the good stuff will start to roll off the production lines.  At present electrical storage weighs more than gas storage however electricity is weightless and IMO I think the latices that could store electricity should weigh no more than the gross weight of gas and tank.  

I can feel it in my bones, pure electrical energy in a light weight vessel will be seen in my life time, and how to get electricity directly from rudimentary combustion is doable as every thing has an electrical exchange before heat is produced. Solar research will uncover how to utilise most of the suns bandwidth.  95% of what hits a solar panel will convert into usable energy.  Already they are working on fast diode switching to achieve these goals.

[SilverSurfer]

This is off the hook!   Glad I found the thread!  Big fat kudos!!!   Will write more when Ive had some experience,  right now,  Im getting a plan for a mission!  Thanks.   Silver Surfer.

[John-uk]

What ya thinking silver surfer. ?