ElectricGod
10 MW
Thanks guys for the encouragement. I was going to build it no matter what. I've already bench tested the motor and relay and know for a fact that motor RPM is higher in delta than it is in WYE for the same voltage. I've read quiet a few ES threads on this subject and decided that the best solution to all the FUDers out there was to not listen to them and just build it. Let the cards fall as they may. I have no ego to bruise if I fail. I'll readily post that wye/delta switching if it sucks...why it sucks and why I think it sucks. I have no agenda to prove or some stake that I'm right and you're wrong. All I can say in my defense...if you want to call it that...is I'm going to try it no matter what anyone says....good or bad. To my own personal gain will be the knowledge that it worked or didn't...that it had XYZ caveats and ABC benefits. After that...anyone else is welcome to follow my thread and repeat what I did or not. It's not like I'm pioneering something new. It's already been done. It's fact that more Kv means more motor RPMs for a given voltage. A motor when it reaches that magical 80% or so of full RPMs starts dropping off it's torque band. If one can then increase it's torque band say by an additional 1.7, well that means the motor keeps on pushing for a good while longer until it reaches that new 80% or so of it's new torque band. I think I'll take advantage of that cool little detail and make myself a "2 speed" motor. The other side of that coin is current. I'll be running at 82 volts at first. The motor in WYE will draw something like 50-60 amps WOT from a dead stop. I take those numbers from my kick scooter which runs the same motor at 82 volts as well. If I were to switch to delta and do the same test, my current draw would be significantly higher and my battery pack would run down faster. So most of the the time (all of the time from a dead stop) WYE will be what is used. You simply get more torque for the same amps out of WYE. Then when I need another kick in the pants to pass that car or just to show off or whatever reason...who cares...switch over to delta once WYE starts petering out. There will be a current draw penalty, but then delta wont see as much use as WYE will anyway.
Thanks for everyone's input. I'll post my results when I have them. I'm going to optimistically say that it's going to work out just fine. Will there be lessons learned and mistakes made. I sure hope so! I've already popped a couple of mosfets in a cheap controller testing this out. Lesson learned...don't switch under throttle and let the motor slow down some before switching from delta to wye. Of course I've read a load of threads on the subject and just about everyone said to not do that. As a result, as soon as I knew my set up worked as expected, I was trying out all the things they said NOT to do. I wanted to see what would happen for myself...on a cheap controller that I didn't really care about. On the real 10Kw controller that will run this motor...well I'm not going to deliberately blow it up. The end result is I blew up a few dollars worth of IRF4110's...no big deal...I have loads of spares and they replace easily enough. And YUP...sure enough switching while under throttle or switching down too soon blows them up. LOL!
Laptop batteries...off subject, but I brought it up to make a point about ignoring the FUDders. My scooter weighs 120 pounds and goes 50mph with my lardo 240 pounds riding it on level ground...while I'm standing up and creating loads of drag. It goes a bit faster if I scrunch down and current drops a few amps. And that's on laptop cells. Yes it takes quite a few more of them to get the same amperage and capacity that new EV grade cells would deliver, but so what...my batteries cost me nothing. I can pull something like 30 amps at 1C and I know because I've done it, they will do 3C or 90 amps. How much current do I need? Well that's plenty for my scooter and I'm only running at 12P...on used/free laptop cells. I really can't complain at all. Anyone who has access to used laptop packs in sufficient quantities, I strongly recommend they collect the cells and do what I did...as long as they set their expectations correctly. Look in my signature for the URL for my battery build thread. There's lots of laptop and battery holder builds in there.
I'm going to continue to ignore the FUDders. A really big number of posts an expert does not make. I'm smart enough to figure out how to fake the system and the mods. I could very easily mine ES for all kinds of content and then repost it as my own and make my number of posts jump from a mere 868 as of this post to many thousands in a matter of days. A little software and a little knowledge of how ES works and I could be a gigawatter in a month. LOL...anyway, not accusing anyone of doing that...just saying that lots of posts doesn't make someone more knowledgeable than someone else. When I first got on ES and had like 1 watt...LOL...I couldn't believe how the FUDders came after anything I said. It was like I was fresh meat at a bashing party. I ignored them all and eventually they stopped the nonsense. One of those FUDders told me "how dare you correct one of us" You are no one on here with your 10 watts or whatever it was. We are all gigawatters. We know what we are talking about. I then pointed out that I went to school for electrical engineering and wasn't some wet behind the ears kid at nearly 50. Did that suddenly engender some respect? NOPE...LOL...it was all about their egos and my measly 20 posts. OK so enough of that.
I'm moving ahead with this build and yes I agree, I'm not an idiot and I personally can live without a wye/delta safety feature (numb nuts filter) on my relay. However, that little piece of hardware is for others who are numb nuts or ignorant and would do an inappropriate switch that blew up their controller. So I'll build the numb nuts circuit, try it out and then I can show a way to more or less make your wye/delta switching be idiot proof.
The motor controller arrived today for this build. I have way too many simultaneous projects going. I really want to focus on my Currie scooter conversion, but new toys are new toys.
Thanks for everyone's input. I'll post my results when I have them. I'm going to optimistically say that it's going to work out just fine. Will there be lessons learned and mistakes made. I sure hope so! I've already popped a couple of mosfets in a cheap controller testing this out. Lesson learned...don't switch under throttle and let the motor slow down some before switching from delta to wye. Of course I've read a load of threads on the subject and just about everyone said to not do that. As a result, as soon as I knew my set up worked as expected, I was trying out all the things they said NOT to do. I wanted to see what would happen for myself...on a cheap controller that I didn't really care about. On the real 10Kw controller that will run this motor...well I'm not going to deliberately blow it up. The end result is I blew up a few dollars worth of IRF4110's...no big deal...I have loads of spares and they replace easily enough. And YUP...sure enough switching while under throttle or switching down too soon blows them up. LOL!
Laptop batteries...off subject, but I brought it up to make a point about ignoring the FUDders. My scooter weighs 120 pounds and goes 50mph with my lardo 240 pounds riding it on level ground...while I'm standing up and creating loads of drag. It goes a bit faster if I scrunch down and current drops a few amps. And that's on laptop cells. Yes it takes quite a few more of them to get the same amperage and capacity that new EV grade cells would deliver, but so what...my batteries cost me nothing. I can pull something like 30 amps at 1C and I know because I've done it, they will do 3C or 90 amps. How much current do I need? Well that's plenty for my scooter and I'm only running at 12P...on used/free laptop cells. I really can't complain at all. Anyone who has access to used laptop packs in sufficient quantities, I strongly recommend they collect the cells and do what I did...as long as they set their expectations correctly. Look in my signature for the URL for my battery build thread. There's lots of laptop and battery holder builds in there.
I'm going to continue to ignore the FUDders. A really big number of posts an expert does not make. I'm smart enough to figure out how to fake the system and the mods. I could very easily mine ES for all kinds of content and then repost it as my own and make my number of posts jump from a mere 868 as of this post to many thousands in a matter of days. A little software and a little knowledge of how ES works and I could be a gigawatter in a month. LOL...anyway, not accusing anyone of doing that...just saying that lots of posts doesn't make someone more knowledgeable than someone else. When I first got on ES and had like 1 watt...LOL...I couldn't believe how the FUDders came after anything I said. It was like I was fresh meat at a bashing party. I ignored them all and eventually they stopped the nonsense. One of those FUDders told me "how dare you correct one of us" You are no one on here with your 10 watts or whatever it was. We are all gigawatters. We know what we are talking about. I then pointed out that I went to school for electrical engineering and wasn't some wet behind the ears kid at nearly 50. Did that suddenly engender some respect? NOPE...LOL...it was all about their egos and my measly 20 posts. OK so enough of that.
I'm moving ahead with this build and yes I agree, I'm not an idiot and I personally can live without a wye/delta safety feature (numb nuts filter) on my relay. However, that little piece of hardware is for others who are numb nuts or ignorant and would do an inappropriate switch that blew up their controller. So I'll build the numb nuts circuit, try it out and then I can show a way to more or less make your wye/delta switching be idiot proof.
The motor controller arrived today for this build. I have way too many simultaneous projects going. I really want to focus on my Currie scooter conversion, but new toys are new toys.
