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Old 05-14-2012, 10:15 PM
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Thumbs up Controlling three phase motor with joystick

I made a control interface which accepts a standard PC joystick and provides a +/- 5 VDC signal to the Variable Frequency Drive (VFD). The motor automatically reverses depending on the polarity of the signal. The control interface also has a PIC18F4420 which has 5 active ADC channels which will read battery voltage and current, and DC link voltage and current. It drives a 2x16 character LCD display. It will also have an RS232 or USB interface to a computer which will log this data for later inclusion in a spreadsheet which can graph these quantities as well as power, efficiency, energy usage, and other quantities.

Here is a short video showing what it does:
http://youtu.be/R3gu4KSAgyI

I can provide circuit details and PIC code if anyone is interested. This is not a finished project but I will soon wire up the resistors to an op-amp so that it will actually be able to connect to the battery and link voltages, and shunts for monitoring the currents. I will probably start with a simple RS232 connection to stream the data to a PC, but I may replace the processor with a PIC18F4450 which is the USB version. That will be more convenient for newer computers. But I will most likely use one of my spare older computers which run Win98, XP, or Vista. Since I will be using this on an off-road utility vehicle (converter riding mower or garden tractor), it needs to be rugged and/or expendable.

It is also possible to use an Ethernet-enabled PIC so that the tractor will be essentially a web page server which can be connected to the internet through my WiFi router, or maybe directly to an Android Net Tablet, like my Archos 7, or an iPhone. It could also be set up for remote control.

I may also use the X-axis of the joystick so that I can operate two VFDs and two motors, one on each rear axle. That could make the vehicle a zero turn radius (ZTR) machine. The possibilities are limitless and exciting, but "gittin' 'er done" is the kicker!
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Old 05-15-2012, 12:48 AM
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Default Re: Controlling three phase motor with joystick

consider fly-by-wire and canbus.
The joystick is both the throttle control an brake control as well as steering.
my implementation I did back in late 90's use Motorola 56F103. I am upgrading all my nodes to STM32F4
As a toy I am putting a 3 axis accelerometer on a glove with finger strain gauges to replace the Joystick and switches.
So the motor is not directly control but is access through its Canbus node.
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Last edited by bjfreeman; 05-15-2012 at 12:54 AM.
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Old 05-15-2012, 01:11 AM
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Default Re: Controlling three phase motor with joystick

the STM32F4 is canbus, Ethernet, Serial, with Camera support for visual Identification. Has an Audio, SD and one wire support. through the one wire is hooked up a Wifi that is the remote monitoring and control Access point.
The SD lets you have files local to the node. you can also have programmed audio files for give verbal responses.
you really don't need a PC.
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Old 05-15-2012, 01:15 AM
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Default Re: Controlling three phase motor with joystick

you might look up the DIY Drones page for their system. it is all open source.
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Old 05-15-2012, 02:16 AM
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Default Re: Controlling three phase motor with joystick

I just read through your web page and it's very interesting to see what you have done, and plan to do. I'm rather astounded at the amount of power you are talking about. That 400 kW motor is a beast, but I wonder if you really need that much power. And $250,000 is some sticker shock! I found a 150 HP motor on eBay for $2500, and I bet it would do the job. If not, there's a 500 HP motor with VF drive for $30,000.

I went through some approximate calculations for a 30,000 lb vehicle with 400 lb of passengers and a 6000 lb 500 HP motor and a 6000 lb 100 kW-hr battery pack. For a nominal 3% grade it would take about 200 HP to maintain 60 MPH, and for a 12% grade it would take 550 HP to maintain 40 MPH. These are within the capabilities of a 300 HP motor unless you have a very long steep grade. So, maybe the 500 HP (or maybe 4 150 HP motors) would be better, and you get better efficiency if you stay within the conservative ratings.

Thanks for the info on CanBus and FlyByWire. They are overkill for my simple utility vehicle and tractor projects, but they could be good test beds to try some things like that and I can scale up.

As for the joystick control, I found that it does not hold its zero position very well, and I need to incorporate a "deadband" where the motor will stay off. I have just an analog circuit directly producing the DC signal from the joystick, which is just a 150 kOhm variable resistance. So I will probably need to feed the resistance signal to the PIC and produce the control voltage using PWM, although there is still some problem with the +/- output. Maybe I can just disconnect the analog signal until the PIC reads a certain range and then drive the motor controller. I don't really need very slow speeds. Probably 600 to 3600 RPM will be fine.

Also, I might use the trigger buttons for start/stop.

Thanks!
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Old 05-15-2012, 04:37 AM
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Default Re: Controlling three phase motor with joystick

the final design is four 250KW 3 phase Squirrel Cage motors. two of which I have installed. One as a generator the other driving a 4 speed manual. Once the new "axle" is manufactured, for the four wheel, some time in 2013, then we will get serious.
the data as far as horse power was not calculated but taken from Bus conversion HP ratings. Most Grey hound type Buses are 400HP, but RV find the 600HP gives them the oomph to climb long grades in the mountains we have on the Cascades (3,000 to 10,000 foot passes), an Olympic mountian ranges, and have the extra kick to pass. Heck we have city streets that look almost vertical.
Granted that is over kill for people that just drive where the land is relative flat.


HEV is not conservative, or economical from a cost point of view. It is about environment cost, and what we will have if we don't stop polluting.
My goal is to have a Hydrogen run vehicle with recharge on the go. on the go meaning not having to use fill stations.

The Joystick I first had was dual reverse resistance. I then went to 90 degree offset hall effects.
I used the thumb switch as a dead man switch. The trigger was the passing Gear. Have not figured how to do that with the glove yet.

In the classified he has the siemens 96KW 3phase that I paid a lot for, now used $500. I noted those here that have used them for their cars.
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