> From: Otmar <[EMAIL PROTECTED]> > To: [EMAIL PROTECTED] > Date: Tue, 1 Oct 2002 18:28:24 -0700 > Subject: Re: SepEx Motors and Controllers for EVs > > > I have developed a few sep-ex drive systems for low voltage > industrial use. My programmer and I made one on Zilla platform > running a sep-ex ADC 9" motor for his Honda Del Sol conversion. It > works pretty well, but there are drawbacks. > > As discussed before, the motor design could use interpoles, which we > don't have on ours. In order to do low speed regen in the controller, > the high current section that drives the armature needs twice the > silicon of a series drive. Then there is the increased complexity of > the small H bridge field controller. > > Overall I decided that in the volumes we are doing, for the hobbyist > market, a AC drive makes more sense. The incremental cost in silicon > for AC drive is not that big anymore, and the benefits are numerous. > > -Otmar-
Hello all, As usual, Otmar is correct in his assessment. We at NetGain have spent a lot of resources trying to develop a Sep-Ex motor and controller package for the EV community. Building a Sep-Ex motor turns out to be the easy part. Building a Sep-Ex controller is another story. When using a series wound DC motor in a Sep-Ex configuration, interpoles are a necessity. The problem with most motor designs utilized by EVers is simple - their small internal size does not allow the physical space for interpoles ... unless you undersize the field coils and de-rate the motor's horsepower. In order to maintain the horsepower that EVs require - a larger diameter motor is needed to house the primary field coils and the interpoles. Physical space may allow small interpoles in some motors - but more room is required due to the interaction of the magnetic fields created by the field coils and the interpoles. A time consuming series of tests (called "Black Band Tests") is used to adjust the air gap between the field coils, interpoles and armature. By tightening or enlarging the air gaps between them - you adjust the interaction of the magnetic fields. Once optimally adjusted, easy to duplicate in production. Today, we have a 13" diameter motor with interpoles. We could develop an 11" with interpoles, but have not found it to be financially viable ... yet. The biggest problem we have encountered is in controller design. Few controller manufactures will even consider developing a system for the relatively small EV market. Those that have -- have priced themselves out of it. We are still looking. When we find a controller manufacturer who can produce a quality product at a reasonable price -- we will have Sep-Ex motors available. Until then, an AC system is the more logical choice. Kevin Zak NetGain Technologies, LLC
