Looks like one of the moderators has brought all the info from Paul's 3 phase controller thread, to this thread. Thank You to whoever did this.
Now for some more information: From my contact in Spain. We had discussed using the Lebowski chip, but, Lebowski said he had no time to get into the code writing, researching, so, here we are.
( I know someone that could design any inverter IGBT or MOSFET (paying him of course) if we had the controller, but controlling an AC induction motor is the most complicated/costly part, and using a commercial VFD is not safe neither efficient)
(e-assist motor can work at 65V (500A) with the delta modification. I think it is a good voltage for a 15-20 HP motor
It is a delicate modification but anyone with welding or plumbing knowledge can do it. It is necessary to use silver wires to weld the copper wires (to increase conductivity of the union)
(I would never pay an external company for such a project, it is extremely complex and the know-how would remain outside. Any further modification would require their additional work (and charges). And also you would never have a SW free of errors, because any error detected after the project is considered closed would have to be discused to decide if it enters in the warranty or not, which causes the project to be ethernal in time.
I worked on SW companies for years, and I know how they work)...
(At the moment I own a company that is focused on SW for dynamometers (sportdevices.com). My interest in electric motors is basically to create a tool for measuring all important features of these motors like the efficiency, with the motor + controller as a "black box" (not controller alone, or motor alone). For this reason I am doing some investment in several commercial parts as motors and controllers. At the moment I have two Curtis (80V) and one Sevcon Gen 4 (which I couldn't start by now). And 3 e-assist motors and one ME115 water cooled motor.
I am spending some money to not have to develop any hardware by now, but in the long term I have the aim of developing my own inverter and controller, but as this is very time costly and we have lots of pending tasks related to daly work it is being delayed and delayed.
(There is an electronic engineer in the company (for this reason I told you that the inverter can be done here), but the controller SW should be written by me, and this is not possible at the moment).
(If we could arrange a team to cooperate to build such controller, we could provide all inverter design for a high power application, say 150V and 500A for Mosfets or 400V 400A for IGBTs, but it should be very carefully arranged and coordinated to no end in a total failure project
Also we can provide some tools for measuring purposes, we build software and electronics for inertial and braked dynamometers, and recently have tested a simple extension to measure battery and current voltage (efficiency is motor power / battery power)
(The point with ACIM motors is that it is not enough it works like PM motors (there are lots of controllers for PM motors: sensored, sensorless, BLDC, vectored, etc), it also has to be "the best one" because control strategy and parametrization in ACIM motors is a whole, if it is wrong the motor will draw a lot of heat and current. For instance for the same torque you can have higher slip (frequency difference with actual speed) and less current, or low slip and high current. There is an infinite set of combinations current and slip that provide different efficiencies for same torque. And also there are several combinations depending if you need max absolute torque for a specific rpm or max efficiency (it could be simplified to two operating maps).
As you can see it is not enough the controller works, it has to be also optimal and provide several modes of operation (for PM motors this is almost fixed). Self-tune process is also important as most of us would not be able to do it manually, but for that a high level of knowledge about ACIMs has to be reached.
(It is not so simple as adapting a PM controller to ACIM. PM can even work with a simple "BLDC" control (something similar to activate the right switch as the motor turns) and including the V/F parameter (KV) for that specific motor, but ACIMs need vector control to work in an efficient way. V/F algorithms are totally not recommended for traction applications).
(My main concern is investing too much in ACIM motors (parameter measurement, efficiency maps, etc) and discover afterwards that people mostly use PM motors, then I would have wasted most time
But also, I can see that there are much more solutions for PM motors, so I am not sure if could provide some interesting solution to improve what is already available. Honestly, I am bit lost)
(using a voltage converter is not a good idea, in general it would be a bad design:
* it increases the losses (minimum 10 or 15%)
* it adds a lot of weight and volume to the vehicle (the transformer for 15KW is huge)
* it increases the complexity and probability of failure
* you only save batteries in series (and BMS), but you add the converter
* you still not simplify the motor inverter, which still needs to operate with the motor voltage
* currents are multiplied to values that could be simply ridiculus. For instance if inverter and motor handle 400A, the converter (for 1:2 conversion) would handle 800A or 900A, which starts to be simply too much
for me it makes much more sense simply put more cells in series which will also add range and keep the current values low).
(Keep in mind that a converter over 500W or 1000W starts to be very big. Something over 3 KW is very big, and something to reach 15 KW simply does not make sense (it will take more room and weight than the batteries, for sure)
(Regarding kelly, I never tested them, probably they are worse than Curtis controllers)
(With the Curtis 80v 350A I got about 16 HP at 55V. With the 550A version and 75V I expect to be about 30 HP or more)
ALL the info in parentheses is the info from my Contact in Spain. He has purchased the Curtis controller. Cost $2400.00 +/- USA dollars
He also gave me permission to post our discussion. My part was merely asking questions that he so graciously answered.
One part about the voltage boost converter will pertain also to Paul's thread.
OK, lets get this thing working.