# Soleq Sepex Controller



## evtkw (Feb 27, 2010)

For all (or any?) of the Soleq EVcort owners out there,
I have replaced the Soleq sepex motor controller in
my EVcort with a pair of Kelly controllers, and outlined
the project here:

http://home.earthlink.net/~evtkw/

While the Soleq Controllers were an impressive design
feat, they tend to fail periodically. Repairs to the
all analog, 100 pound controllers have been unsuccessful for
me and others I have contacted. 

My new configuration works fairly well, and I am able to 
get 200+ Amps regen and decent performance. I guess the 
system could be used for any sepex motor.

Let me know if you have any questions about the system, 
and I will be happy to give any information I can.


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## AmpEater (Mar 10, 2008)

Why not one of the kelly sepex controllers? Any more info on the 2 controller rig? I didn't see any on the website (at a quick glance).


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## evtkw (Feb 27, 2010)

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.


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## AmpEater (Mar 10, 2008)

evtkw said:


> 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.


I looked again and it's all there, right at the top. Duh. 

How about *"KDC12603,24-120V,600A, Separate Excited with Regen"*?

Is this a newer offering than your setup? I was planning on purchasing one of these soon, or rolling my own from two controllers like you did. Your experience is certainly helpfull


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## evtkw (Feb 27, 2010)

This seems to be a new controller since I built my system. I originally tried the model below this, the KDH12403, and it didn't have enough power for my fairly heavy car. However, they have upped the current, so It may work, depending on your application. I would talk to the Kelly tech support to see if they think it will be good for you as well - they were very helpful to me when I was building my system.

If it is powerful enough, it certainly seems to be a good option...


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## Tinbendr (Mar 6, 2008)

Looks like you removed quite a bit of weight. How much NET loss did you have?


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## evtkw (Feb 27, 2010)

I'm not sure how much weight was removed - maybe 150 pounds? There is a big box of parts that didn't go back in, and I can barley move it...


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## DawidvC (Feb 14, 2010)

evtkw - very nice solution and very nice conversion

For people attempting to do something similar:-

If you want to control the field weakening automatically, you need to monitor armature voltage and motor speed. If you reach maximum armature voltage ( actually we normally use 95% in industry), you start weakening your field until you reach your *minimum* field current at *maximum *motor speed. For this you need some form of speed feedback device.

I hope this is helpful
Dawid


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## major (Apr 4, 2008)

DawidvC said:


> For this you need some form of speed feedback device.


Hi Dawid,

The Curtis and Sevcon SepEx controllers which I have used do not need a speed feedback device.

major


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## DawidvC (Feb 14, 2010)

Major

You do not need any feedback device if you do not do field weakening with torque control. If you use a setup like mentioned here, where you have a manual control over your field weakening, you will likely only experience a loss of torque if you forget to reset the field back to a higher value. However, 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.

Regards
Dawid


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## major (Apr 4, 2008)

DawidvC said:


> 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.


Hi Dawid,

The commercially available SepEx Curtis and Sevcon units will let you select speed or torque control. It has been a while and I don't remember which I used on which vehicles. I do know I tried both ways and neither required speed feedback. In fact, neither had such provisions. Now maybe those did have clever software. On the other hand, I used a SepEx GE golf car motor with a Curtis. The motor did have a speed sensor. So I suspect the programmers at GE aren't so clever and use speed feedback on their SepEx controllers 

I do not know how Tim is set up to match field and armature currents. But I do not see where he has a speed feedback in his controller installation. And it is unclear if he has any automatic adjustment for the field or if it is all manual.

To me, the important parameter to monitor when controlling the field of a SepEx motor is the armature current. This is done in the Curtis and Sevcon by entering a field map. Once you have this, there is no need for shaft speed. Maybe it is clever programming, but these controllers are able to set speed limits as a percentage of maximum speed and get reasonable results. I actually had 3 different speed limits on my vehicles, fast forward, slow forward and slow reverse. 

I do not see the need for speed feedback unless precise travel speed is critical for your application. And I imagine it is better and easier to properly program the controller using currents instead of speed, although I have never done it.

My 2 cents worth,

major


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## evtkw (Feb 27, 2010)

I used the most simplistic system - just a knob on the steering column that controls the field current. I set the field to full current up to the motor corner RPM for the full field current. I then reduce it to increase motor rpm manually. This was basically the only system available 2 years ago for a high power system - at least that I could find.

I have considered adding a small circuit to automatically adjust the field current based on motor RPM - I already have an RPM sensor that feeds into the stock tach, so it seemed the easiest solution. I thought to do it in 3 to 4 steps, so it would feel like an automatic transmission...

Of perhaps some interest is how the original Soleq controller operated. The controller would run in torque mode with maximum field current up to the corner rpm for max current, with the accel pedal controlling the armature current. For higher rpm, armature current is no longer controller; the controller adjusted the field current to control the armature current based on pedal position - so kind of a constant power controller.


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## DawidvC (Feb 14, 2010)

Major

I had a look last night in some of my references. Here is a quote from one of them:



> 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.


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.

Regards
Dawid


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## pm_dawn (Sep 14, 2009)

Hi !

Here is also a controller that might be useful for those SepEx motors running over 100v.
http://www.elektrosistem.com/e/p2.htm
The Phoenix can be gotten in 120v versions both for the 600A and the 800A

First hand info, you can get from a guy here at the forum.
Search for volvo 440.

Best Regards
/Per


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## toyolla2 (Jun 21, 2010)

This is my first post here !

I was involved with a field controller for a Sepex 36vDc @400A controller back in the early 80's. At that time I used a Motorola MC34060 PWM chip.
The chip had the usual goodies - on chip osc. and 5v precision regulator - but with the added feature of having *two* op amps feeding the PWM generator.These error amps were active high and wire or'ed together at the active input of the PWM comparator. Thusly whichever commanded the minimum output would dominate the loop.

Accordingly one op amp was fed the max field current reference on one input and the actual ground referenced field current feedback on the other. The field current sensing resistor was a 0.1 ohm able to carry the 9 amps of max field current IIRC. 

The other op amp was supplied 0 to five volts from the accelerator pot which represented the 0 to 400 amp armature current command. 

There was one other input to this op amp. This was the armature current feedback and it was a little more tricky. For this, we took the Kelvin connections from a 500Amp 50mV meter shunt located in the path between the armature negative lead and battery ground, and fed them thru' matched 1k resistors into one section of an LM358 acting as a differential amp with similarly matched 100k feedback resistors - supposedly avoiding any unexpected offset voltage and also providing a voltage gain of 100. The LM358 op amp output was then scaled with a preset pot to yield 1 volt per 80 amps before sending it on to the PWM chip. 

The single ended PWM output was fed via a base current limiting resistor to a TIP147 plastic PNP 10Amp transistor which sourced current from the high voltage bus to the hot side of the field winding. This technique facilitated the ground sourced field current feedback on the other side of the field winding which I described earlier. We wired the field with RF cable but 14Khz with 85nS risetimes pretty much wiped out AM reception on the vehicle plus any nearby vehicles also ! 

Once we got the RC network across the chip's armature error amp sorted out the operation was quite stable. And driving above base speed with the armature controller bypass contactor energised, we could set the motor amps instantly anywhere on the meter that we wished. 

I was able to brag at the time that we were indeed able to control 400A with a $1-50c transistor and a $2-30c PWM chip. Then I happened to mention that field control above base speed could provide 400A of regen virtually for free, even 1000A no biggie. 

So now I really needed to have a voltage offset at the output of that LM358 which I had previously took pains to avoid. Accomplished, in the event, by lifting the leg of the ground ref'd 100k resistor and joining it to +2.5V pedestal which would similarly raise the op amp output by 2.5v. This gave the accelerator pedal input still sweeping from 0 to 5v effectively a +/- capability about zero armature current. Well we did it. And it worked. Our admittedly limited powertrain gave field control from 12mph to 45mph in 1st gear.

Looking back I often wondered why those members with series wound motors didn't consider rewinding them for shunt fields.


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## major (Apr 4, 2008)

toyolla2 said:


> 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 toy,

Welcome to this forum. You have a pretty good memory for details about your 25 to 30 year old project. Do you remember what motor you used?

Anyway to address your wonderment: The primary reason is that there are no readily available motors and controllers for what I call medium voltage, on-road power range. That is like 120 to 200 volt battery packs and up to 50 kW. And of course, everybody wants more power. And low cost.

So what is most used is like a 9 inch diameter series wound motor. It is basically a forklift motor which has had the brushes advanced to successfully commutate at higher voltage than it was designed to handle. Since these guys use the transmission from the donor car, the motor is unidirectional. Several companies offer PWM controllers to suit these applications. A downside is that series motor/controller systems do not regenerate. Everybody seems to want regeneration, but in fact few would benefit much from it. 

So you have done a low voltage low power SepEx system and wonder why these guys don't rewind and go SepEx. First, who rewinds for them? Who designs the field? Where do they get the controllers? And then how do they deal with the brush advance and commutation? Easy, you might say. Go to interpole machines. Where do they buy interpole machines? And who funds all this? 

I suspect if you had a source which would offer SepEx regen capable motor/control systems at a similar cost (perhaps a slight premium), you would get a fair amount of business from the DIY converter market. So, put that good stuff in your memory banks to use and do it. See if I'm right. 

BTW, I have a 96V, 800A series interpole system with regen. It's a good 30 years old and uses SCR controller. I've also done a number of 48A, 400A SepEx systems in the last decade. I have been really been impressed with the modern SepEx controls. The old series regen system sucked in comparison. But then again, it is totally discrete technology. Programming by soldering in a different resistor 

I've also worked with ACIM systems. That's the way to go, if you can get it 

Regards,

major


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## toyolla2 (Jun 21, 2010)

Part One

_First, who rewinds for them? Who designs the field? Where do they get the controllers? And then how do they deal with the brush advance and commutation? Easy, you might say. Go to interpole machines. Where do they buy interpole machines? And who funds all this? _

Hello major,

thanks for responding. Actually I have a poor memory but these projects stand out in my mind than what I do for a living. Anyway to answer your question...

The motor was either a GE CM377 400A 28Vdc ASG or a similar Jack &Heinz which we sourced from Princess Auto in the years when they were putting ex War Department equipment into consumer channels. Those aircraft starter generators were quite plentiful in 200A, 300A and 400A versions. I would imagine there are quite a few 'survivors' even today - I have one still. Some were 6 pole and had fluted commutators - apparently done for high speed use.

We were able to procure the declassified manuals on them as well. It should be said that although deprecated by some, these examples of 1950's aviation history were in fact excellent machines ! Granted, their armatures were stiff as molasses to turn - primarily due to excessive (to us) brush pressure, but when I checked it out they fell within the max lbs/in/in that was stipulated. Of course with a 3000 Hp aero engine shaft just a couple of feet away the generator brush friction was probably never a cause in consideration for aero fuel efficiency particularly when it came with the promise of the highest reliability. Needless to say, that didn't stop attempts, and ultimately futile attempts if I remember, to secure a source of weaker spring steel for that delinquent brush gear.

Because of the high unloaded shaft torque and of course the knowledge of its previous life as an aircraft engine starter, it gave cause for some to believe that it was more of a_ low speed / high torque motor_. In fact the motor was qualified for service at the low figure of 66lbs-ft despite a gas guzzling 1000A although calculations said it should be good for around 88Lbs-ft. Ah..... perhaps maybe the 22lbs-ft shortfall was that brush friction !! 

But Low speed machine ?? If you run the math taking into account a propellor speed of 2500 RPM then a 3:1 planetary step up would certainly have it spinning at a fast clip. If its operational life does in fact find it mostly within the 8000-7000rpm range then clearly it fits more closely in the domain of the high speed machine. I notice even the Tech Manual supports its legacy as a high speed machine specifying an electrical top speed of 10,000 rpm and requiring mechanical certification to 11,000 rpm.

When you read the manual it makes you want to see the test rigs that they were using to recertify these machines and would be required for the regular mandatory maintenance. 

Unfortunately most of the ASGs that fell into the hands of EVers found service coupled to the clutch plate of a 4-speed transmission where they rarely saw much more than about 2250 rpm before a gear upchange.

When I came on the scene, however, there was no suitable electronic field controller in existence for EV's to allow the upper register of the motor speed range to be put to use.

As a first step I started in on the construction of a PWM field supply. This conferred the ability to fix the shunt field current without regard to variations in the winding temperature nor the voltage rail. The task of always having to find a suitable ballast resistor also went away. My sales pitch was that PWM would give us the freedom to ignore the previous conservative field setting and place our shunt field excitation at an optimal setting. The intended topology was to utilise a high side switch but I also knew to do that I needed to overcome the problem on the ASG winding schematic which depicted the negative shunt field lead joined internally to the negative armature lead.

This join, wherever it was hidden, would also be covered in baked varnish. It was possible to make out several well crimped and soldered joints sheltering underneath blobs of varnish The enabling technology was to discover how to inject a current thru the motor so we could estimate which one of these junctions contained the elusive negative field wire. We used sharp probes to penetrate suitable candidates. You're looking for millivolts here. Then we needed to reinsulate everything that had been dissected and rebake the motor. But that needed the whole motor to be disassembled in order to bake the stator alone. What a job ! We did two other motors later on. One of which was actually miswired and the mistake covered over in varnish. Hmm.. so much for aircraft quality standards !

A bench test was now conducted for armature iron loss evaluation whereupon it was determined that the maximum armature voltage should not go much above 36Vdc. At least that explained why some who had been running their motors at 72Vdc found their motors running hot. We were able to announce that at 72Vdc (4500rpm) we had been able to separate out, somewhat unexpectedly I might add, approx 2.2KW of armature iron loss.

Previously the impression I wanted to leave from that post was to give a descriptor for simplicity that a SEPEX field controller could be constructed using readily available parts. 

In this post since you asked about the motor I thought to add that a SEPEX motor can throw a curve ball at you. Field control is not necessarily plain sailing just because you get the electronics right as this post attempts to outline. 
T2


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## toyolla2 (Jun 21, 2010)

Part Two

major you ask _And who funds all this ? _

Well, as I saw someone here succinctly write (on controller pricing) 

*"It is not the underpriviledged who get into electric car conversion because they need to save money on gas.* *This is an expensive hobby."*

There is, however, always going to be an element who want to do something with an aged clunker, a motor from a fork lift, and some discarded ignition/lighting batteries they happen to have lying around and need advice *now* on how to pull it all together with a large roll of duct tape. I am not saying I am against the idea of helping out the underdog, but sometimes I feel that I am being asked to advise the captain of the Titanic - after he's hit the iceberg.

---originally Posted by *toddshotrods* 
_The current DIY EV community is a strange dichotomy of green and/or economy minded transportation and racers. The two don't really mix, and their needs are on opposite ends of the spectrum. Making things more complicated for the racers is the fact that the market is dominated by the green/economy side._

I think that *toddshotrods* has nailed it right there. As you and I both know, you can't find a reliable controller at the lowest price point. It doesn't exist. However, that fact alone has not stopped more than a few falling prey to those rascals who talk up their under tested prototypes and then inevitably either haven't provided themselves with enough financial cushion to honor warranties or just flat out refuse service. I fear the chances of their clients re-entering the market again to more legitimate providers is slim to none. 

What is the incentive to enter the controller market and build an excellent product like over at Cafe Electric ? That vendor is then left with the much smaller market niche of people willing to fork over $5k or $6k. Couple that to the fact that as a vendor you are still at risk from doubtful wiring practices since you can't be sure that qualified people will be overseeing the installation of your product.

_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 ? Isn't it just the same number of ampere-turns going from series to shunt. The interpoles don't enter the equation surely ?

Continuing on the rewinding topic - because I happen to think it's important. Seriously I think we should be of the mindset to rewind for lower voltages and safety. Costs aside, what the ultimate reliability of a 576Vdc string of li-ion batteries is going to be will be interesting. The MTBF of these cell packs has not yet been quantified. 

I'll put it out, in case you may not be aware, that ACMOTOR (Red Suzi project) on the AEVA site, had an 11Kw ACIM rewound from 415Vac to 100Vac in August '09. Sure he had to shell out the $700 plus the extra $200 for three embedded thermistors and rotor balancing for high speed, but he reports significantly improved performance using a 10.5:1 ratio. That's a drop from 8V down to 2V per Hz. 

In essence ACMOTOR took a perfectly good running motor and rather than regard it as a done deal he proceeded to put a $900 investment into it. Whereas others would rather have seen the money go on something more tangible in the form of more batteries for 830V battery strings, he has chose this way to go.

I suggested to him that next time he might think of going as low as 0.75 V/Hz like GM's IMPACT on his next project. He responded that he is standing pat for now since this would require an upgrade in both controller and batteries. 

Getting back to SEPEX motors frankly I feel their time has come and gone. It would be interesting to construct a compact side by side two motor transverse cradle able to drive each rear wheel individually as Greenmotor Sports has done but with SEPEX in place of ACIMs.

In '85 after talking with staff at Transport Canada I submitted such a proposal along with photographs schematics and graphs.

In my proposal, based on my field controller work, I outlined how you could utilise two motors in a current sharing scheme. It proceeded in three phases. The system would start in Phase 0 with the motors in series with a single armature controller and their fields set to max. 

At 10mph or 100% modulation thereabouts Phase I would be entered for field control. In quick succession, the bypass contactor would short out the armature controller, one field would be operated to make its armature pull constant current under control of the accelerator pedal while the other field controller would be referenced with a Vbat/2 resistive divider and the actual midpoint voltage. The second motor would therefore act as constant voltage device. I doubt you would disagree that it makes for a stable system to have a constant current source driving through a constant voltage system. 

Phase II, the final phase would be entered when field current has dropped to a (previously determined) level which has effectively halved the flux in the two machines. At this point restoring both the motors back to their maximum field current should enable each of them to support the full battery voltage alone. They may therefore be switched in parallel and their analog inputs suitably arranged such that both receive the same pedal input with the second motor field controller now receiving feedback input from its own armature current sensor.

I would use a mix of both microprocessor and hardware supervisor ccts plus additional commutating and quench diodes to ensure integrity of the switching operations when sequencing from Phase I to Phase II. 

A racer might use a 500 amp armature controller to get the vehicle rolling to around 30mph before the field controllers can take over and then run a constant 2000 amps or whatever throughout the last two phases. The system doesn't rely on speed feedback either. Although personally I have no problem with a Red Lion setup with a toothed wheel, a two wire sensor and an LM2907 chip, just don't ask me to do the mechanics of it !

The concept appeals to me because you get to use the shunt wound machines as rotating amplifiers thus avoiding the armature current rolloffs experienced when making the same switch with series field motors. Then there's the avoidance of stressing a large array of semiconductor devices under extreme conditions. Of course the system is amenable to being brought up at greatly reduced currents and system voltages since I can see it would really harsh someone's mellow to inadvertantly zorch a siamese set when playing around in unfamiliar territory !!

BTW anyone who thinks I went off topic, go see the first post in the thread.

_For all (or any?) of the Soleq EVcort owners out there, I have replaced the Soleq sepex motor controller in my EVcort with a pair of Kelly controllers, and outlined the project here._


The originator of the thread hi-jacks his own topic in the first sentence. *evtkw*, man you should get some sort of an award for the fastest hi jack in history.

Bye for now
T2


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## major (Apr 4, 2008)

toyolla2 said:


> _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 ?


Hi T2,

You sure write a lot  But this one question is the only attempted answer I can see. I'm sure most stator rewinders _could _rewind DC fields. But will they? I think you'll find that most motors of the size we're talking about are throw-aways as far as rewinders are concerned. Motor shops which specialize in forklift motors even buy replacement field sets as opposed to winding. Yeah, there are places to do it. But finding one is no easy task and you're likely to pay more for the rewind than you did for the motor 



> Isn't it just the same number of ampere-turns going from series to shunt.


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?



> The interpoles don't enter the equation surely ?


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.

Good example is that aircraft generator you mention. Who would have thought a 24 volt 8 kW generator would need interpoles? Forklifts use motors in this range without interpoles all the time. Why then does that aircraft generator not only have interpoles, but also compensating windings? Because of the varying range of excitation and load and the fact that it is also used as a motor for engine starting.

I like SepEx systems. I wish there were such systems available for the EV in the voltage and power range needed. But few have the means to _rewind_ the series motor fields and _design_ a field controller. And contrary to what David thinks, you still need an armature controller. So after all the trouble and expense involved in converting the series to SepEx motor, you still have the basic system (meaning the expensive armature controller) which you had to start with. And for what? Regen? Yeah, nice. I like regen. But where is the value here? A mile further on a battery charge? That is an expensive mile 

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. 

Regards,

major


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## toddshotrods (Feb 10, 2009)

major said:


> ...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.
> 
> Regards,
> 
> major


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.

Series is the best universal solution for DC. The same controller that works for the guy with a grocery getter can push my racer down the track, or vice versa. True, he may not need that much controller, or I may not have enough (with his) but the point is they're almost plug-n-play for whatever you want to do with them.

As for my quote you posted - it proves the point against SepEx. The people who would pay for it - like me - won't see the benefit in it. The people who could really use it, won't pay enough to get it.


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## toyolla2 (Jun 21, 2010)

Hello major 

Ok perhaps I haven't addressed all your questions in the way you'd like. I'll try to answer you again.

_Go to interpole machines. Where do they buy interpole machines ? And who funds all this ?_

Well, the easy answer is - the Customer - but you deserve more respect than that. I'll discuss motor design issues first.

Regarding original interpoles and compoles - they will scale against the armature current as before - no problem there.

Brush skew whether in the presence of interpoles or not - also not a consideration providing the direction of motor rotation remains unchanged, since field flux is already nonlinear wrt to field ampere-turns anyway except perhaps in college text books, that is. 

Nevertheless the max armature current must coincide with the setting of brush skew for optimal commutation particularly for racers who ought to build a test rig for finding the best results. Let the war be won in the lab not the battlefield. There is no room for either Plug'n'Play or remote expertise like mine, if you must insist on pushing the performance envelope.

_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 ?_

The main field should be merely the restoration of the original ampere-turns through the use of smaller wires and lower currents but with more turns. It should be easy to determine the wraps of the series field when removing it and the motor plate should give some idea of rated armature current.

The new field current should be a combination of something an existing single transistor can live with, along with consideration towards the lowest rail voltage likely to be applied in practice. That way the resistance of the new (shunt) field can be chosen from a selection of wire guages to allow sufficient voltage headroom for the field controller current regulator under worst case conditions. You might actually want to leave more headroom than that even, to enable a faster slew rate of field current for fast crossover to the regeneration side to be possible. If regen is important to you as a vehicle control mechanism beyond recuperation. 

The good news is that, excepting brush skew as noted, the requirements are a lot less critical for DC than AC.

You mentioned a prefernce for AC. How do you mange there ? Since it is common knowledge that for AC, the design of the power electronics module requires much more knowledge about the load it is to drive which is why AC Propulsion went so far as to insist, back in 2004, that you purchase their motor along with their drive.

My regards

T2


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## toyolla2 (Jun 21, 2010)

Hi Todd

you wrote,

_The people who would pay for it - like me - won't see the benefit in it._

Todd, a Sepex motor allows an increases in the area beneath your system power profile - I am truly sorry if you can't see the benefit. Otherwise it's one of those "I can explain it for you but I can't understand it for you" type of situations. 

Over at Cafe Electric, Otmar has a 'text' drawing to graphically show the 'mountain' shaped profile a series motor gives despite the Zilla being at 100%

The same armature inside a SEPEX stator by comparison is vastly superior. It would encompass both the mountains of the siamese powertrain depicted. 

- *toddshotrods *_Series is the best universal solution for DC_.

Yes I agree, there is enough mechanical skill and knowledge at work here without you needing to be burdened by yet another discipline. 


My rregards 

T2


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## toddshotrods (Feb 10, 2009)

toyolla2 said:


> ...I am truly sorry if you can't see the benefit. Otherwise it's one of those "I can explain it for you but I can't understand it for you" type of situations...


I don't pretend to be on you or Major's level of understanding but I have this knack for being able to see things that are above my head, and finding ways to captilize on them (even without full understanding). It's the entrepreneur/competitor in me.

That being said, I do see the theoretical benefit. That's what I started chasing when I found out my motor is SepEx. I see that it seems _possible_ to have the best of both worlds in one neat, tidy, little package with the SepEx configuration; massive torque off the line, and maximum motor speed down the track. Two motors in one. I purposely just brought this discussion down to the language, thought patterns, and needs of the average racer; in case one should read this thread and wonder what the heck all this techno mumble-jumble has to do with them getting from point A to point B, ASAP.

The problem is the investment of time, money, and effort needed to get there. You have an academic approach to this. The problem with that is it takes massive funding, and nearly unlimited time, to produce appreciable technological advancements from theory. I just visited the OSU CAR team's facility, where they are working with manufacturers to develop tomorrow's (electric) transportation, racing electric open-wheel cars, and running electric streamliners to new records on the salt. All very nice and awe-inspiring, but far removed from the world outside those college walls, where government and private business funding don't flow like water.

In the time it would take me to develop the theory (for my specific application), design and develop the hard parts, then test and tune them, to build a SepEx motor I could have built two or three series motors, bought a top-of-the-line controller, and went very fast. So comparing the two possible routes, I don't see the immediate benefit in being the first to develop a SepEx solution.



major said:


> ...You want to prove your point, make a controller for Todd if it is so easy.


Exactly. You build it, we will come. I am developing a vehicle to serve as a marketing tool for my business, using the best *available* EV technology I can find. I am not trying to become a controller developer/manufacturer. That is just not my path.




toyolla2 said:


> ...Yes I agree, there is enough mechanical skill and knowledge at work here without you needing to be burdened by yet another discipline.


I will reserve judgment, and try to give the benefit of doubt, since this is the internet but that statement makes you sound like an arrogant snob. I hope that you didn't mean it that way, and that you can see how it can come across that way because:


toyolla2 said:


> ..."I can explain it for you but I can't understand it for you"...


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## major (Apr 4, 2008)

toyolla2 said:


> Hello major
> 
> Ok perhaps I haven't addressed all your questions in the way you'd like.


Hello T2,

Maybe because I answered your wonderment with my own questions.


toyolla2 said:


> Looking back I often wondered why those members with series wound motors didn't consider rewinding them for shunt fields.


Let me put it in a simple way. They cannot afford to. Or believe that the series wound solution better meets their needs. 

Nice discussion here, but until there is an affordable SepEx package for these guys, things will remain the same. Only a brave few will venture into the SepEx zone. And I doubt it will be drag racers. If you're interested, search this site and you can find a few examples of guys running SepEx where I have assisted in the application. Jackbauer comes to mind. An exception to the norm. He built his own control. 

Regarding the AC system, it was basically a trial and error development in the lab and on the track. After a few years and a bucket full of money, we got a pretty good system  Looking back, it would have been cheaper and quicker to simply buy the ACPropulsion system. But not near as much "fun". Especially because our competition was using ACP drives.

At any rate, glad to have you aboard.

major


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## JRP3 (Mar 7, 2008)

Toyolla2, it sounds as if you are saying a Sepex motor would be a better choice when paired with a non existing controller. Zilla and Soliton1 are available for series motors at 1000+ amps and 300+ volts, yet Sepex controllers that I'm aware of max out at around 600 amps and 120 volts.

Regarding AC induction motors and matching drives, Curtis does have controllers that can be adapted to different motors, though admittedly limited to 550amps and 120 volts. Others have used modified industrial VFD's to run their motors, check out etischer's build. Reinhart Motion will build you a custom drive for your AC motor, for a price.


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## JRP3 (Mar 7, 2008)

toddshotrods said:


> I will reserve judgment, and try to give the benefit of doubt, since this is the internet but that statement makes you sound like an arrogant snob.


I don't think that was his intent. He was merely agreeing that there is enough to do when building an EV that learning how to build your own controller, or build your own motor for example, is beyond what most people want to tackle. I'm sure I could eventually learn both but that's not where my, or most people's, interest lies.


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## major (Apr 4, 2008)

toyolla2 said:


> a Sepex motor allows an increases in the area beneath your system power profile - I am truly sorry if you can't see the benefit. Otherwise it's one of those "I can explain it for you but I can't understand it for you" type of situations.
> 
> The same armature inside a SEPEX stator by comparison is vastly superior.


In theory this works great. But in practice, it just does not pan out when you are looking for maximum performance, such as on the drag strip.









This is Mike's Crazyhorse Pinto. If you attempt to field weaken the motors to fill in the dips, you will find that you lose torque and actually become counterproductive. 

Mike has built this with commonly available parts, like Warp9s and Zilla 2k. Run a budget to do a SepEx version.  That's why you don't see Mike rewinding to shunt fields.

You have some great ideas there T2. I'd love to see a demonstration. Show me a time slip 

major


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## toddshotrods (Feb 10, 2009)

JRP3 said:


> I don't think that was his intent. He was merely agreeing that there is enough to do when building an EV that learning how to build your own controller, or build your own motor for example, is beyond what most people want to tackle. I'm sure I could eventually learn both but that's not where my, or most people's, interest lies.


As I said, I'll reserve judgment. T2 is obviously fairly intelligent, and has good command of the (American) English language though. The words people choose and how they string them together often have more meaning than what appears on the surface. I've been in business my entire adult life, and am now a Communications major - I tend to pay more attention to hidden communication than the words people say or type.

Back to the point. As it stands right now, the best place for used SepEx motors is with tinkers who like experimenting; be it for curiosity or budget constraints. For a person building an EV for daily transportation, working on getting everything working properly could be a fun/rewarding experience. For a business trying to develop a profitable product, or a racer trying to compete successfully, it's just not currently a wise choice. Maybe if there were twelve serious racers all with the same motor, and substantial budgets, it would make a little more sense to develop a controller for that specific motor - maybe. My guess is the twelve racers with the series motors, and equal budgets, will beat them anyway because they'll be spending their money _going faster_, not trying to get up to pace... The cold hard reality is the momentum swung in favor of series, just like it did in favor of gasoline way back when. It takes a huge effort and a lot of time to even catch to, up let alone overcome, society's inertia.

I came to this realization about SepEx the hard way. I was determined that I was going to discover and exploit its potential. I ended up on that path because I did see and understand the benefits, as much as my untrained brain can anyway. Then, I woke up and smelled the coffee - saw the world around me.

I think series DC will continue to rule for drag racing and budget conversions, for a while. Eventually though, I think AC is going to rule the day for all forms of racing, and all medium to high budget conversions. I actually see myself going AC eventually. JRP3 is already running AC, and happy with his conversion. EVnetics is inching closer and closer to developing a higher power AC controller. Feel the momentum? Sense the inertia? Can you imagine where that would leave all those random, obsolete, SepEx lift motors? I say in the scrap yard, rewound series with recycled field coils, or in the hands of tinkerers - all low budget solutions. Why would any sensable business person invest in developing a new product for a dead-end market?


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## toddshotrods (Feb 10, 2009)

major said:


> ...If you attempt to field weaken the motors to fill in the dips, you will find that you lose torque and actually become counterproductive...


Unless I misinterpreted his point, I think he was suggesting that there wouldn't be a dip. There would be one large mountain that climbs more progressively to the summit. Starting with full field, and full torque, you can develop a curve for field weaking that transistions you from torque-bias to max rpm, over the course of the same run. That's what I was after.

The problem, especially for drag racing, is you have to have a very intelligent controller that can understand, compensate, and react in milliseconds. Things happen very, very, fast in a drag race so we count on our equipment to do the job reliably and consistently. Actually, the more I think about it the autocross course may be even more demanding in this regard. Constantly on and off the accelerator, asking the motor to comply in a fraction of a second without fail. Who is going to spend the time and money to develop it, test it, and deliver it to me in a neat package with a friendly user-interface, that allows me to keep my concentration on the million and one other things I have to do?

I was actually almost ready to beg EVnetics to do that for me, and then thought about it from their perspective - for what gain? I can develop a much more beneficial business relationship with them if I concentrate on making their available products work in my application.


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## major (Apr 4, 2008)

toddshotrods said:


> I think he was suggesting that there wouldn't be a dip. There would be one large mountain that climbs more progressively to the summit. Starting with full field, and full torque, you can develop a curve for field weaking that transistions you from torque-bias to max rpm, over the course of the same run. That's what I was after.


That's my point Todd. Ain't goin' to happen  The loss of torque will outweigh the gain in speed, so decrease power. Counterproductive.


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## toddshotrods (Feb 10, 2009)

major said:


> That's my point Todd. Ain't goin' to happen  The loss of torque will outweigh the gain in speed, so decrease power. Counterproductive.


Ahhh, I see. You've just confirmed my path to series.  That was the only possible benefit I saw in playing with SepEx. I'll just concentrate on making massive doses of series-wound torque then. 

With series torque, and ultra-light weight, I should be able to run numerically lower gears in the differential, giving me the top end I need. I think that's the key - series is actually capable of everything the average driver or drag racer needs. Regen is the only thing it can't do, reasonably, and that is not a need.


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## toyolla2 (Jun 21, 2010)

Exactly, JRP3 thanks for helping me out there with Todd. 

And thank you major for your encouraging remarks. I hope I can be productive here but like most everybody else I'm here mainly to learn from others' experiences. 

I have been involved with semiconductors and motors since 1972 and I like to think that what I do is simple. 

Of course when I try to explain a new idea it sometimes it comes down like a 2 by 4 on my head when I realise how much infrastructure knowledge is needed to understand it.

For instance I introduced the concept of the constant current source. I don't think most people on this board know what that really means, but I address it to the few that do. 
And you know who you are.

To be fair, you could also find many competent electronics techs who would have trouble recognising a motor carrying 2000Amps with 90 volts across it behaving as if it were a high impedance source unless they had actual experience in the field either.

- Todd my experience is that EVers are self reliant people who know above all how to get things done. However it's my opinion that the successful ones also know it's not what you know but whom you know.


In my case I formed a mastermind group with help from a local entrepreneur. And I don't have to pay them just yet ! But we had a meeting to get everyone on board on my project. Following that we use a mailing list for ongoing communications. The important thing is they were all selected for their different skill sets. I'll give you an example.

At our first meeting it was decided I should get to meet with a federal official. Well, delivering a short technical presentation in a formal setting was something I had done before only a couple of times but this was to be more of a face to face meeting. Then I had the idea of asking someone in the group who looked to be a good 'front' man to come along. Not being overly technical in engineering himself he said he would play the role to unwind some of the technicalities whenever he sensed that my presentation was getting too far away from the target audience. In the event, that was exactly what happened. The outcome was successful and later on 'doors were opened' as they say. 

I was wondering whether you thought about asking someone at the local EV club to be there for a second opinion whenever you embark on a purchasing spree on the electrical side. I'm not an expert, but I have cash is a situation to be avoided. But it's a trap I've fallen into when I need to convince people I'm a serious buyer and not a tire kicker. On the other hand to say - I'm not an expert, but my friend here is, so what's this deal again - is where you need to be. 

BTW I was sensitive to coming off as obnoxious. Below is the final version in my files but somehow never got sent out. I always keep a file backup about every hour because the system has a habit of logging me out and deleting the entry window. It happened yesterday and I hadn't backed up late enough and had to spend yet another hour re-inventing my wheel !! 

Other times I come back to the computer forgetting my most recent version was amended in the files and promptly finish off the earlier version that happens to be still residing in the browser window. So Todd, with block and copy to the rescue, this is what you were supposed to have seen, hope this fixes the problem. So re your situation -


_Yes I appreciate that there is enough mechanical skill and knowledge involved here already without being burdened by yet another discipline. _

_T2_


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## toddshotrods (Feb 10, 2009)

This has been fun guys, but it's time to flush now ...


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