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I have a full wiring diagram with parts list available for anyone who wants one.
> I'm assuming this is a standard series golf-car motor controller. I've > never tried one with an ET motor, but I know others have. A couple of them > have posted here in past years. In the other designs i was given a DPDT switch was used to control F/R. Thats easy. Problem is how do you guarantee that the armature will never see power unless the field sees it first. The answer i got was essentially "be carefull". They way to do that is to have the F/R switch control the controller, and all your safety switches control the main solenoid. That means i need to get a positive signal to the curtis when in forward, no signal when in center off, and positive signal again when in reverse. To do this i have to take the two POS leads from the DPDT switch (1 pos fwd and 1 pos rev) and feed them into those micro relays. > The video clip is fine as far as it goes, but it left me puzzled. It does > show that the motor reverses, but it doesn't explain what the relays are for > or how they're connected. (Maybe that'll be in next week's episode. ;-) Those two micro relays then turn on the controller. The micro relays are essentially preventing a short in the DPDT switch. Doing this i can guarantee that: The Curtis may only turn ON when field voltage is applied, and only if the main solenoid is powered up, and only if the 4A fuse that i installed on the field is powered up, and only if the thermo sensor on the motor is happy. > Even better would be a reed relay that sensed field current > instead - that would prevent enabling the controller if a relay connection > broke or fell off. If a relay broke or shut off the controller would shut down. No power to armature. > It should work, if you provide some means of ensuring that the field is > powered before you apply voltage to the armature. I suppose you could do > that with a relay, enabling the Curtis's KSI only if field voltage is > present. That is exactly what i was able to do. Crappy video. Late night... > One gotcha remains, however. Without a full field in series with the load, > the ET motor may not have enough inductance to make that Curtis happy. Its > current limit may not be able to react fast enough to protect it from > overcurrent. The symptom of this in road EVs is rough, lurching starts when > pulling away from a stop. > > This is the best (and by far the most entertaining!) explanation I've read > of how this happens : > > http://www.evdl.org/pages/hartcontroller.html > > If the controller is sufficiently oversized, it might survive just fine, at > least under normal operating conditions, but there's still some risk. > > > David Roden - Akron, Ohio, USA I cant say that i don't understand that completely, but the current always has 36V in this design. Unless you plan on adding field weakening which is simple to do. You would just need to add your resistance to a single wire. And this isn't so much about using a Curtis. What i wanted to do is create a generic design that would work safely with ANY standard series golf cart controller that has high pedal disable. A kelly or alltrax or whatever..... The goal was safety, universality, simplicity, cost. Like i said i have a diagram if anybody wants one. Please tear it apart. I want to know what is wrong, and what is right. I would like this to be the start of a simple ET controller wiki. |