Hi, I'm completely new there. It's my first post, so feel free to tell me if I did anything wrong. I wonder if this is the proper category, but I had to start somewhere and it seems like a good place to go.
I'm trying to build my own electric car, with custom motor driver, battery pack etc. And yes, I know that this is VERY hard thing to do, but I've been collecting information about the process for about a year now. Since the title of the topic talks about the motor control, this will be my main focus, but I will provide some more information, maybe they're useful.
So... I want to use an AC induction motor in my vehicle. About 20 kW. It's rated for 55V AC in delta configuration and has 2400 rpm rating. It comes from an old traction lift. I consider other motors, but I will talk about it later. I wasn't able to find any reliable information about whether 55V delta voltage stands for amplitude of line voltage or RMS line voltage. Or maybe something else?
My plan was to use IRFP4468 for my power stage. Is this a good selection, or should I look for something else? I actually own a few bags of these, so I'd prefer to stay with them. I initially wanted to connect 2 or 3 of them in parallel for each segment of 3-phase H-bridge (so 12 or 18 total) and use IR2110 connected in parallel to drive them, but I've read somewhere that although it will work, it's not the best solution possible. So do you guys have any suggestions what I should consider?
Okay, here starts the hard part: the control board. I designed my very crude SPWM inverter using constant V/Hz, but (surprise...) it didn't work out well. I was using STM32F103 as microcontroller, and using one of it's timers to generate 3 PWM signals. It can post the code if you want, but I don't think it's necessary, since I abbadoned this idea. I then found the STSW-STM8020 library. It features the V/Hz control of ACIM drives. But then I found the paper describing EV car conversion with Field Oriented Control of AC induction motor (ACIM). I will leave link to it at the end. So after some Googling I found the STSW-STM32100 library, which supports FOC. Unfortunately, it supports only BLDC/PMSM FOC, not ACIM FOC. I found that the previous version of it had supported the ACIM FOC. However, even the succesor of STSW-STM32100, which is MC SDK for CUBE-MX doesn't support ACIM FOC! Could anyone explain me what's going on? Did I miss something, or is ACIM FOC some stupid idea that is totally unsuitable for application?
Talking about FOC: the real reason why I'm writing this post is to get information on how to implement it for ACIM. I know the basic principle: you convert the 3-dimensional coordinate system to the 2-dimensional, convert current vectors to the rotation vectors, then move the rotor vector, calculate the new current vector values and convert it back to the 3-dimensional coordinate system and then feed PWM with the calculated voltage values. However, it is just too complicated for me. I found some implementations on PIC microcontrollers, but I have never programmed PIC's before. I know Atmel and STM a bit (I'm not an expert, but I've already done many projects on them), but not Microchip. So if anyone could provide me with working example of ACIM FOC implementation, or at least with the required equations and explaination on how to implement them im STM32/ATmega, I would be really, really grateful.
Maybe you're asking yourself 'why won't he just use the BLDC/PMSM motor?'. The answer is simple: the price. The AC motor I'm talking about costs around 200 US dollars, my DC alternative (6 kW, 48V) also around that, while BLDC's are much, much more... I could of course use the commercial solution, but point of this whole thing is to make something by my own. I'm aware of this project difficulty, but I will be really happy if you made an effort into explaining me how to make it working and fulfil my ambition. If it will be too hard - it's okay, I have the working plan B with DC motor.
Links:
STSW-STM8020
https://www.st.com/en/embedded-software/stsw-stm8020.htmlSTSW-STM32100
https://www.st.com/en/embedded-software/stsw-stm32100.htmlPaper describing car conversion (that's how I would like my project work like, except that it doesn't have to be sensorless)
https://www.ajol.info/index.php/ijest/article/viewFile/64009/51809IRFP4468 datasheet
https://www.infineon.com/dgdl/irfp4468pbf.pdf?fileId=5546d462533600a40153562c73472019Thanks in advance!