Paul & Sabrina's cheap DIY 144v motor controller

[MPaulHolmes]

Donovan had suggested some special low temperature solder that I think I'll try. I still haven't spent the money for a new attempt, since we're trying to get our first house. I'm going to get just a couple mosfets, 2 diodes and then test it that way with my new fake motor. That won't be too expensive. But I'm about to start teaching for the summer, and I'll have classes from 7:30am to 9:30pm with almost no breaks for a little while haha.

[electricstorm]

I am about to start testing the control board and had a couple of questions.

Adam, I ordered the RS-232 to USB adaptor board from Digikey. It didn't come with any software or instructions. My question is do I need any drivers for this board on Windows 7 (64-bit) and do I need to change any jumpers on the board to allow it to work with RTD Explorer?

Michael, in using the two resistors to fool the controller into thinking it is getting a signal, do I connect the current sensor to the controller up and once powered on connect the voltage divider or is the controller powered up and the voltage divider connected to simulate the current. Also, do I need to connect the throttle pot?

Thanks guys!

[apowers]

electricstorm

When I got a usb to rs232 the driver that came with it was not windows 7.
I downloaded the driver from manufactor's site.

I think the resistor divider takes the place of the sensor.

And without pot you might get high peddle error.

Alvin

[MPaulHolmes]

Ya, you need 2.5v to trick the controller into thinking that there's a current sensor there. To do that, just use like a 2.2k (or whatever you want) and a 2.2k from 5v to ground, and pick the middle as your 2.5v point.

And as my ex-brother in law would say, you definitely need the pot.

[electricstorm]

Thanks Paul!

I don't have a scope, but my electronics instructor said to bring it in and we would use it as a class lab to use the scope to check the signals. I'll still have to set the values to allow me to see the waveforms (kpi and something else I think!) before taking it to class. Should be interesting anyway for the class. My instructor thinks it's great and to tell you you and the rest of the contributors have done a fine job with this open source project.

Jim

[adamj12b]

Originally Posted by electricstorm

I am about to start testing the control board and had a couple of questions.

Adam, I ordered the RS-232 to USB adaptor board from Digikey. It didn't come with any software or instructions. My question is do I need any drivers for this board on Windows 7 (64-bit) and do I need to change any jumpers on the board to allow it to work with RTD Explorer?

Michael, in using the two resistors to fool the controller into thinking it is getting a signal, do I connect the current sensor to the controller up and once powered on connect the voltage divider or is the controller powered up and the voltage divider connected to simulate the current. Also, do I need to connect the throttle pot?

Thanks guys!

You should just be able to plug it in. If not, you can get the driver here:

Virtual COM Port Drivers

-Adam

[electricstorm]

Thanks Adam!

I bought the one you gave me the link for a while back (bought two of them). It's just like the one in your videos.

Thanks again!!

Jim

[Frxdy]

Oh,No, Something is wrong. For three months almost every morning I read for half an hour or so. Now, suddenly, there are no more pages, no more "Last>>". YIKES! I have come to the end of the thread! Oh man! Now what will I do each morning? I know.... start soldering!

[princeton]

I haven't seen this thread in a looong time. Admittedly, I didn't go through all the pages. Has anybody thought about a reverse circuit for those of us using designs without transmissions? If this has already been discussed, it's ok to cuss at me.

[bennelson]

Originally Posted by princeton

Has anybody thought about a reverse circuit?...

That's real easy and isn't part of the motor controller. If you look at nearly any wire diagram from Curtis, Alltrax, or any of the other commercial motor controller manufacturers, they all show how you can have a "reversing contactor" as part of the circuit.

A reversing contactor normally completes the circuit, but has a second set of power connections, that when actived, breaks the circuit, and then reconnects it with the polarity reversed.

On a permanent magnet motor, you simply reverse the positive and negative, to make the motor spin the other way.

On a series-wound motor, it's just slightly more complicated - you need four power connectors going to the motor (two for the field, and two for the armature) and the reversing contactor just reverses one or the other to make the motor spin in reverse. (If you reversed BOTH the field and armature, the motor would still spin the same direction.)

If you look at a typical electric forklift, that's exactly how they work. The motor is connected to the wheels through a differential, and reverse is done electrically through a reversing contactor. Drive motors will always have four power connector on them. Series-wound pump motors sometimes only have two, as those motors are usually designed just to run one direction.

Also, be careful of brush timing is you want to reverse your motor. If you advance your brushes for higher voltage, they will be retarded for reverse!

Some commercial motor controllers also have a pin in for when you are in reverse. When the controller knows you are in reverse, the controller limits speed to half.

On my Electric Geo Metro (With an Open Revolt controller) I just use the mechanical reverse gear, and I have every bit as much speed/power in reverse as I do in forward - actually even more, as reverse gears tend to be even lower than 1st, and I NEVER use first gear in my car because of how much torque the motor has.