I looked again and it's all there, right at the top. Duh.The complete design, including pictures, schematics, and configuration, is on the web site. I hope it is working properly for different browsers...
This car requires up to 400 A of drive and over 200A of regen at 108V. I don't believe that any controller maker offers a sepex controller with this kind of full size EV capabilities. All of the off the shelf sepex controllers are for golf carts.
Hi Dawid,You do not need any feedback device if you do not do field weakening with torque control.............if you perform a similar mod and want the field current to automatically adjust, you cannot do it without feedback, or very clever software that can deduce motor speed without actual measurement.
It would seem to me that for traction applications it would be easier to use the armature current reference as a setpoint, which would make it quit easy to use a seperate, small controller as a field controller in a sepex setup. The book referenced also took about field reversal, which is a quick way of reversing a motor, instead of the armature, which would require bigger contactors.It is possible to duplicate this characteristic in a separately-excited motor by controlling its field current by a thyristor drive configured as a current regulator, the reference being derived from being derived from the motor's armature current through either a shunt or a DC current transformer (DCCT).
The advantages of this technique increased motor output (since the resistance of the field windings is not connected in series with the armature) and the facility to set minimum and maximum limits of field current, thus preventing saturation of the magnetic circuit and improving performance under light and overhauling load conditions, e.g. downhill running.
Hi toy,I was involved with a field controller for a Sepex 36vDc @400A controller back in the early 80's..........Looking back I often wondered why those members with series wound motors didn't consider rewinding them for shunt fields.
Hi T2,First, who rewinds for them ? I haven't researched it but I am sure most stator rewinders could work on DC windings. What am I missing ?
Well, yeah, kind of. At what load do you consider to figure the AT for the series motor? And at what voltage do you use to figure the SepEx field?Isn't it just the same number of ampere-turns going from series to shunt.
Interpole windings depend on the armature. But the point is, the series motors most of these guys have do not have interpoles. They get away without interpoles because it is a series motor and they have advanced the brushes. Change that motor to SepEx and vary the field and reverse it or generate with it, and you have big commutation problems.The interpoles don't enter the equation surely ?
My ears were itching... Yeah, I'm probably pretty well on my way to series wound. I thought I had purchased a series motor, was disheartened to find out it was SepEx, then determined to explore its separately excited promise - but the return on investment (of money, time, and effort) is just not there. There are just too many variables to make it a worthwhile pursuit, especially for a community of wide-ranging goals and ideals....And you quote Todd. Good example. He is building a hot rod EV. And has a monster GE SepEx motor he wants to use. However he is considering having it rewound to series because he cannot get a proper controller for it. You want to prove your point, make a controller for Todd if it is so easy.