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| Thread ID: 80375 | 2007-06-20 11:22:00 | any electric motor experts out there? | motorbyclist (188) | PC World Chat |
| Post ID | Timestamp | Content | User | ||
| 561097 | 2007-06-22 06:57:00 | now i do appreciate the advice, but: 2kw is the max power to register as a moped, and it isn't for (legal) road use, it's just for fun/learning. (i commute on a honda vfr400 and am about to inherit a yamaha R6: 2kw is of NO interest to me for commuting, and $15 a week on gas is not what i call expensive anyway) i KNOW that perpetual motion and "free energy" is bull****, what gave you the impression i thought otherwise? i also know i'll need a bit of battery power, but must i add there are many bikes being produced with more power than this one that run fine on batteries, and they aren't even using lithium (most are still on cheap ol' lead) i also know i'll need a controller! you guys think i'm stupid or something? i've been doing alot of homework and was just wondering if a winch motor would be suitable, which one person so far has reasoned it won't be. for a first attempt i'll use some strong resistors to cut the current down to run the engine at half-power so a pot should suffice for a "throttle", then when a controller is sussed i'll run on full grunt. of course i may abandon this depending on the motor i use, and whether or not that is even possible. and i'll have an emergency kill switch incase anything malfunctions and the engine tries to rev itself to peices or batteries overheat or whatever i would buy a briggs&stratton etek or a perm pmg132, but that is too much power and too much money, that said i may buy one later for a bigger project if i'm still interested. www.electricmoto.com www.electricmotorsport.com |
motorbyclist (188) | ||
| 561098 | 2007-06-22 07:19:00 | I DO NOT think you're stupid..I was just greening ya a little..but I think it would be far better to actually look at some of the small Chinese mopeds that run on gellcells that are showing up all over the place..even here in the US. Just see the simplicity and the actual size of the motor. They are really quite small and they don't carry a lot of batteries either. Now..and before you get all angry..I think the real challenge would be to create a digital-pulsed dc powered moped ...that would be class! Most US cars of snob value have newer styled digital motors for the heater-a/c blowers..and that's a good jumping off place. They usually show up on the infinite speed systems as they can just add or subtract pulses and pulse length to field the motor...that's a way to stay out of huge switches and circuits. It also makes the motors simpler too. It's an expense vs returns thing for the automakers...plus the clout of technical engineers who have families and houses for which to pay who make things "different" to keep their jobs. . I just think if you attack this from a new angle, I feel you'll avoid the pratfalls of that big dc motor and lots of batteries and hard to control amperages....and possible fires. BTW: resistors are well out of the equation..do you have any idea what size they'd have to be? Or the heat they'll generate and the energy they'll lose? You could rent out as a portable barbecue on wheels. |
SurferJoe46 (51) | ||
| 561099 | 2007-06-22 08:08:00 | you will need somethig like a pulse width modulator speed controll. getting one for that amperage will be exspencive. | tweak'e (69) | ||
| 561100 | 2007-06-22 11:24:00 | I doubt you could buy a "pot" (potentiometer) to control the current. Only to control a controller. The current direct via a pot would be immense in terms of anything commercially available, and using resistors in the current circuit is an extreme power waste. |
godfather (25) | ||
| 561101 | 2007-06-22 11:42:00 | hrmmm, my research shall continue then. (and i was hoping that using less batteries would help the resistor situation, and prevent me burning out a pot, but i suppose a controller would be the way to go for safety) i've been opting for a 600w moped motor/electrics but can't find any on their own, and would need to buy yet another motor to make a "reasonable" machine. if anyone knows where i could find a moped with working motor that would be a help. hell the sellers on trademe don't even seem to know if they're ac or dc |
motorbyclist (188) | ||
| 561102 | 2007-06-22 12:13:00 | I mean to drive the bike by electric power rather than petrol. perhaps i should've been more clear LOL.. I have to admit I was starting to wonder - but then I'd not long finished watching a program about 4WD Landcruisers with winches on the front so it was kinda stuck in my mind :D The motors used on commercial electric bikes that I have seen are more of the design of those used in the Smart Drive washing machines. They are a multi-pole multi-phase motor, built as part of the wheel/hub and the controller generates the supply electronically. Makes speed control very easy and the whole system is reasonably efficient. Regenerative braking helps to recharge the batteries, which unfortunately, are not light. I've also seen kids' scooters that are electrically propelled. Maybe something along these lines but on a somewhat larger scale? |
supertrouper (6665) | ||
| 561103 | 2007-06-22 12:31:00 | that was the plan lol | motorbyclist (188) | ||
| 561104 | 2007-06-23 03:42:00 | Resistive speed control is practical only if you have a field winding, rather than a PM stator . That lets you adjust a much smaller current . Usually, there is a way to switch between series and shunt (or even use compound) connection to get increased torgue for starting, and speed limiting for normal running . A PWM controller for a PM DC motor is a reasonable proposiition . . . the battery scooters use them . It needen't cost too much . Power MOSfets are quite cheap, even 55 A ones, and they parallel quite nicely . Still, I'd expect to smoke a few in the development process . ;) A multiphase AC motor is more elegant, but there are problems with those too . GE found that the electronics to produce the AC for a 100kW motor for their electric car turned out to be a mobile broadband 100 kW radio transmitter (totally illegal) and had to be properly suppressed . :D |
Graham L (2) | ||
| 561105 | 2007-06-23 04:51:00 | Jaycar kit KC5225 is a 10 amp PWM controller, I have used an upgraded 20 amp version to reduce some 12v DC lamp outputs. So the base technology is out there, cheap (10 amp kit is only $29) and scalable. | godfather (25) | ||
| 561106 | 2007-06-23 06:33:00 | Dynamic Controls in Chch are world leaders in this type of technology, they make scooter, wheelchair and forklift controllers. When I worked there a number of people made projects such as you want to do. Try to find someone who has an old electric wheelchair they don't want anymore, try to get a fixed frequency controller, he older variable frequency ones are very noisy, you sometimes hear them on old American TV programs whining away. Unfortunately they are dual channel. The motors will be just what you want as well, perhaps a bit light for a single application. You could try the appropriate department at your local Hospital. They will have plenty of old ones lying around. A Wiz3F2 24 volt 55Amp controller is the one that you want, it is a single channel scooter controller. Get the toggle joystick as well. The fork lift ones are 48 volts so not useful to you. You will also need special batteries, car batts are not good in the long term they can't handle the high duty cycles and deep discharges for long before failing, ok for testing though. |
zqwerty (97) | ||
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