Paul and Sabrina's Cheap 3 Phase Inverter (AC Controller) with Field Oriented Control

[thingstodo]

Originally Posted by arber333

Paul i am working on encoder mount now and will mount it the same way as resolver is mounted. Now since i have open collector A, B, Z signals i will have to pull them up to 5V with resistors. Can you suggest R value? I see you use 1K resistors to protect micro pins. Do i use 1K also, or could i use 4.7K. Or should i rather use 470R to make ports react faster? Or would you recommend changing input resistors from 1K to 470R?
RLS has 20mA draw limit for their encoder chip.

4K7 is fine, in my opinion. The encoder does not need to react fast - it needs to react consistently. If the signal rises high enough to qualify as ON and falls low enough to qualify as OFF that's all that's required. It can look like a sine wave or a triangle even. But channel A needs to rises before channel B one direction, and channel B rises before channel A the other direction. My cables were made of unshielded category 5 solid-core 22 AWG wire, they were unshielded, I used a voltage divider on the signals since it was fed with 24V and the micro wanted a 5V signal, and there were contacts held together with duct tape. It worked fine for testing ... I would do it a bit better than that for the permanent install ... The scope showed is was very noisy, but it worked.

[MPaulHolmes]

Yes I agree with thingstodo. 4.7k is a good pull up value.

[learnerguy]

Hi all,

Can you please guide me with making a 10 to 20 Kw controller for use in motorcycles.

What parts do I have to downgrade and will it be ecnomically viable ?
I am following Paul's instructions on instructables .

[MPaulHolmes]

What voltage will you be using?

[learnerguy]

72 v 40 Ah or any configuration for 3kWh battery.

[MPaulHolmes]

20kW at 72v is almost 300 amp. You could probably use 300amp IGBTs, which are quite a bit cheaper than the 600amp modules.

[learnerguy]

No changes in the pcb board ? I want to make it as cheap as possible.

[MPaulHolmes]

You could use 4.7uF 1206 package capacitors rather than 22uF. You could leave off the comparator for the 3rd current sensor and also leave off the 3rd current sensor.

[thingstodo]

Originally Posted by learnerguy

Hi all,

Can you please guide me with making a 10 to 20 Kw controller for use in motorcycles.

What parts do I have to downgrade and will it be ecnomically viable ?
I am following Paul's instructions on instructables .

My un-informed opinion, and a few un-informed assumptions
- 20 kw = 26.8 hp (I need this for torque)
- 5,000 rpm for a decent small AC motor (it should be higher)
- 2 pole motor (3600 rpm at 60 Hz)
- 72V pack

72V pack is about 50 VAC or 50V rms
20,000W / 50V = 400 amps. For short periods of acceleration. Maybe 5 HP for cruising is under 90 amps. That's still over 2C on your battery pack if it is 40 A-h. Less than 30 minutes of cruising ... much better in town!

I chose a motorcycle that I have heard of - a yamaha XT660 - and used the gear ratios. !st gear gets you about 100 lbs pushing the bike and you down the street. Decent for acceleration. 5th gear is 5000 rpm for 80 mph. Also decent.

The controller is only putting out 100 Hz at 5000 rpm. It can put out much more. 400A IGBTs should be fine since it will take .. not much time ... likely under 2 seconds? .. to accelerate through any one gear. A decent chill plate would get the heat away from your IGBTs. Or you could use a big set of fins ... depends on what speed you would normally drive. air-cooled does not do well under 20 mph.

The parts that Paul is recommending for the board are in the ?$125 - 150? range if memory serves. That is not a big portion of the cost. The ring cap and the IGBTs are expensive. The chill plate .. is sort of expensive depending on if you do it yourself or have to pay someone.

Paul - does smaller DC/DC for the separate IGBT drivers drop significant price? Or maybe smaller caps? I wouldn't think so.

My opinion - leave the controller board the same - reliable and tested - trim cost by using smaller power electronics with lower max voltage, a lower voltage rated cap, and maybe leave the 3rd phase off the current as Paul suggested. There are not many spare pins on the controller for doing pre-charge and interlocks. You may want to use an arduino or some other separate MPU to annunciate any problems and do the interface with the user.

Are you planning to do a production run? Is that why you want to minimize costs? If you are making under 10 I would expect any changes may end up costing instead of saving.

YMMV ... and it's only my opinion ..

[johkim]

Hello!

I am completely new to the EV community, and have been reading a lot of information on EVs online for the last few days. I have an interest in cars in general, and currently drive a modded VW GTI

Not to bore you with too much of my own story, I was just wondering where I would go to learn more about inverters before coming back to this thread and also Paul's instructables. I am by no means a ME or an EE, just an ordinary guy (my background is in civil engineering!), but I dream of one day making my own EV hotrod.

(the reason why I'm asking about inverters is that AC motors, and batteries are something that I understand to some degree, including BMS, at least enough to read and learn, but inverters are quite a bit harder!)

Sorry if I've posted in the wrong section! I just got stuck here hahaha