Paul & Sabrina's cheap DIY 144v motor controller

[_stEVe_]

Hello to Paul & All!!

I too just completed my journey all of the way through this thread. This project is extremely inspiring in that this cooperation is helping to bring EVs into reach for so many more people by reducing the cost and increasing value at the same time. I have pledged my support through the link on Ben's website and I cannot wait to receive the email that allows me to officially place my order. Keep up the great work everyone!

[nubie]

Welcome StEVe


I notice that if you order 200 caps the price goes down by more than half .

Once we finalize a first-gen design for release there should be group buys for all the stuff, that way we save $100's, if not thousands.

To put it another way, the caps are $67, if you get them in batches of 200 they are only $32.

[roverT]

I've taken the 2C BOM from "blowncurtice" with the USD prices and the Australian pricing and tossed it into excel for any one that might want it.

Cheers!

[MPaulHolmes]

Thanks, Steve! 196 pages. Man, the biggest book I ever read was only 100 pages! haha!

Current controller kit cost: I'm not sure. We need a super official every piece list (even every super tiny screw) for version 2C. The problem was that I didn't really know what all the pieces would be until just doing it, since I sort of made up the process as I went along. I will look at Ben's essentially completely finished controller, and write down everything I see before mailing it off.

I'm going to try to drive with it today. I tested the control section with the controller fully assembled, and it works great on the oscilloscope.

FEATURES:
High pedal lockout (hehe. too easy, I can't believe companies advertise this as a feature!)

Serial communications interface (RS-232). You can program it to tell you motor amps, battery amps, or anything else that the chip knows about.

Undervoltage lockout: It shuts off the mosfet driver if the 12v input voltage is too low.

Optical isolation between control section and mosfet driver/power section.

Thermal cutback happens in 8 stages. When the heat spreader reaches 75 degC the current limit gets cut by 1/8, then 2/8, 3/8, ..., 7/8, and finally current limit becomes zero if max temperature is reached.

Hardware overcurrent shutdown: If the current shoots over a specified point chosen by the user (in the range 484 amps to 765 amps. At this point, it's only safe to set it in the range 465amps to about 550 amps I think.

current monitoring.

reverse polarity protection on 12v input.

overvoltage protection on 12v input.

I can't think of anything else right now.

[MPaulHolmes]

I just got back from the first test drive with ben's controller. I was really scared again. I started off easy for a few minutes. I had the overtemp shutdown start at about 60 degC just to be conservative, since I have never actually tested it in the car.

I drove it up some big hills, routinely doing 200-300 battery amps, so the motor amps were even higher. It did perfectly except for 1 time. I decided to floor it from 0 rpm. It latched up the microcontroller. I had to turn the controller off and then on again to reset it. Even the watchdog didn't restart it. That had happened on the other one I was testing in the garage.

We added some schottky diodes to prevent this from happening, and it was difficult to get it to happen this time, but it did happen. I'm of the opinion that when LEM 300 says 300amps, they mean it. It must have been around 450 amps when it latched up the micro-controller. I have a spare LEM 500 that I will install. Then I'll try to latch up the micro-controller again. My guess is that it won't have a problem with the LEM 500, since the LEM 500 voltage output will be lower.

What happens (I believe) is that the LEM output is a bit noisy, so when you are way over 300 amps, the LEM 300 output voltage has some spikes that are over 5v, making it no longer suitable to a 5v A/D input. That can latch a microcontroller (The EVTech list has told me that this can happen).

So, I believe we should change from a LEM 300 to a LEM 500 or 600. Sorry Joe! I mailed yours a couple days ago. It sounds like you will do some hard driving, so we probably need to get you a LEM 500 or 600. It's easy to unbolt the LEM and stick in a new one. You will have to reprogram the microcontroller with the new LEM in mind. I'll make the necessary changes and I can email you the program if you want. Those dang things are like $27! Makes me mad! I'm glad we haven't done a large group order yet! That would suck. I think I have enough from donations to order a LEM 500 for you, Joe. Adrian is sort of far away. Hmm... I'm not sure what to do about that.

Also, I was able to get the base plate pretty warm. It was just laying against wood, which makes for terrible heat removal, so I would also suggest bolting the base to a heat sink or something.

[blowncurtice]

I still have a couple of parts that I can't find prices for in Digi-Key. Could someone please tell me where to find the SN74HC00 for U5A, U5B, U5C, U5D.
Also what is the "LEM500" what part No and where does it fit in the controller.

[blowncurtice]

Sorry just noticed that the LEM 500 is a replacement for the current Transducer HAAS 300-S.
My parts cost so far is AU$303.01 plus the boards and case.

[MPaulHolmes]

Digi-Key - MM74HC00N-ND (Fairchild Semiconductor - MM74HC00N)

I think anything in the family 74HC00 14 pin quad NAND gates would work. Fran suggested to me NOT to use LS or HTC, but I don't know what that means.

Here's the LEM 500:
Digi-Key - 398-1067-ND (LEM USA Inc - HASS 500-S)

[mcudogs]

Originally Posted by MPaulHolmes

I just got back from the first test drive with ben's controller. I was really scared again. I started off easy for a few minutes. I had the overtemp shutdown start at about 60 degC just to be conservative, since I have never actually tested it in the car.

I drove it up some big hills, routinely doing 200-300 battery amps, so the motor amps were even higher. It did perfectly except for 1 time. I decided to floor it from 0 rpm. It latched up the microcontroller. I had to turn the controller off and then on again to reset it. Even the watchdog didn't restart it. That had happened on the other one I was testing in the garage.

We added some schottky diodes to prevent this from happening, and it was difficult to get it to happen this time, but it did happen. I'm of the opinion that when LEM 300 says 300amps, they mean it. It must have been around 450 amps when it latched up the micro-controller. I have a spare LEM 500 that I will install. Then I'll try to latch up the micro-controller again. My guess is that it won't have a problem with the LEM 500, since the LEM 500 voltage output will be lower.

What happens (I believe) is that the LEM output is a bit noisy, so when you are way over 300 amps, the LEM 300 output voltage has some spikes that are over 5v, making it no longer suitable to a 5v A/D input. That can latch a microcontroller (The EVTech list has told me that this can happen).

So, I believe we should change from a LEM 300 to a LEM 500 or 600. Sorry Joe! I mailed yours a couple days ago. It sounds like you will do some hard driving, so we probably need to get you a LEM 500 or 600. It's easy to unbolt the LEM and stick in a new one. You will have to reprogram the microcontroller with the new LEM in mind. I'll make the necessary changes and I can email you the program if you want. Those dang things are like $27! Makes me mad! I'm glad we haven't done a large group order yet! That would suck. I think I have enough from donations to order a LEM 500 for you, Joe. Adrian is sort of far away. Hmm... I'm not sure what to do about that.

Also, I was able to get the base plate pretty warm. It was just laying against wood, which makes for terrible heat removal, so I would also suggest bolting the base to a heat sink or something.

Paul, the LEM300 output is from an op amp that is fed from the +5vdc supply on the control board. The maximum voltage that the output can be driven to is +5VDC. What is more likely happening is that the cabling from the current sensor to the control board is getting induced voltage spikes from the main current carrying conductor. Have you used shielded cable for the connection to the sensor. The cable shield would need to be earthed at both ends of the cable to effectively shield at those currents. The other thing that can be done to make sure the A to D input doesn't go over the +5VDC is to connect a 4.7 volt zener diode accross D9, a 1N4732A would be suitable.

[MPaulHolmes]

so, INSIDE the LEM is an op amp? The cable is shielded, but the shielding isn't grounded. Did you notice D8? The purpose of that schottky was to keep the voltage below 5v on the A/D input.

When this happened before, I saw significant improvement when I switched to the LEM 500 (on the crappy control board that had some bad caps on it), so I assumed that the latching was from voltage spikes. I stuck with the LEM 300 because I wanted the improved resolution, and I thought the schottkys (D8 and D9) would take care of any spikes above 5v and below 0v.

I reprogrammed the micro for the LEM500, and installed it, so I'll try it tomorrow morning to see if I can get it to latch up.