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Discussion Starter · #1 · (Edited)
Hi All,

I have been meaning to build a electric car for some time, and figured the most straight forward approach would be to convert an existing car than building a car from scratch. I wanted a small car, which had readily available spares and importantly looked cool. I settled on the Classic Mini.

I have been collecting parts for some time, currently have an 8in Advanced DC (ADC) motor, a coupe of lynch 200 (LEM) and some Lynch 170 motors. I had been debating which motor to use, either the large ADC motor or two LEM motors in the front subframe. To get the torque required at the wheels I would build a simple gear reduction most likely using the gear reduction in a standard differential.

Last week I stumbled over a classified where someone was selling parts from a prototype car, all the parts I needed for the conversion. The parts included a Yasa motor that made direct drive to the wheels possible, and Sevcon inventers (Gen 4, S8). I figured it was worth a shot using these parts so I made the deal and they are currently now in my garage (gulp!).


So now I better start designing! The idea is to modify the existing mini subframe to accept the two Yasa motors, and drive the front wheels via direct drive. For me to test the inverters I wanted to build a solid base to mount the motors so I will be modifying the mini frame first.


I have attached a pic of one of the motors in the subframe, you forget how small the mini is, the subframe is tiny or the motor is massive! With some mods I think I can get the output shaft of the motor to align with the hole in the subframe for the drive shaft. I will be designing the motor, inverter, coolant pump mounts in CAD and most likely get them laser/plasma cut. Saves me time (I have a 5 month old I need to play with).

Once I have the motors mounted, the next step would be to get the inverters working. I have done some research on the inverters, and can see that getting them to work will be a challenge. They were modified to work in a particular way in the prototype and I doubt they will work in my set up as they are. To modify the programming it looks like I will need a USB to CAN interface and special Sevcon software - this part is going to be the most challenging part (I think). ie getting the software and learning how to work with CAN.

Anyway, this will be a long and slow journey (the mini wont be slow though) so pls check back in to see progress. Anyone that can help me with getting the Sevcon inverters to work, drop me a line!
 

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Discussion Starter · #5 ·
Hi Malcolm.


I know I can get the IXXAT USB to CAN adapter much more cheaply on ebay, just this weekend one sold for £100. The issue is that they are all V2 and i may need a V1 since the Sevon controller is pretty old. I think the V2 does work but there are compatability issues with the Sevcon software. Also i have found very little online about the size 8, most people use the smaller versions. I figured i would modify the subframe to fit the motors and inverter and then i can start testing it to see if it would work using the basic wiring diagram (long shot). If not i would have to get the adaptor and software and start modifying settings.


The motor worked with the inverter in the past so in theory the motor/inverter programming should be already done.


Its a bit tight in the subframe, well spotted i will have to remove a bit of the subframe at the back and make sure the motor does not hit the steering rack. it will be tight but think it can work. Hoping to model it all in CAD first. I think the CV joints can take a fair bit of misalignment but i'm going to try and minimise it as much as possible.
 

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Discussion Starter · #12 ·
I've wanted to purchase and build and N600 for years and your project is very similar to what that would be.

I think I would start with all the components on the bench and see if you can't get them wired as they would have been in the prototype. I think you should have all the pieces? Did it come with the throttle? That will let you sort out the wiring diagram for the car, too.

The motors are pretty big and i should really secure them before testing. I may as well mount them in the subframe and test then as in both scenarios (testing on the bench vs in subframe) i'll have to make similar parts.
 

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Discussion Starter · #13 ·
YASA's product page for the 750 shows front and back plates (perhaps needing only a cover at the shaft), but of course the motors can be purchased in various configurations. Unfortunately the photos from the classified ad (and the discussion which preceded it) are now gone, so I can't see what these motors look like on the back.

Looking at the original transaxle, it appears that these motors will need to be installed back-to-back anyway to get roughly original axle shaft lengths. I don't know how much shorter the relatively narrow-track Mini could tolerate.
I plan on having the motors back to back, definitely not enough space between them to fit batteries. I think there is a cooling benefit there too since both motors will see the same coolant.
 

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Discussion Starter · #17 ·
Great to see another classic mini project in the making, Im organising a stand at the IMM in bristol showcasing EV conversions alongside the new BMW EV. Be good to see you there!
Will be keeping an eye on this thread as i havent seen this setup used before.

Hi, would like to come but will have to confirm nearer the time. Ideal place to buy mini parts!

Any photos?
None yet, will hope to get parts drawn up on CAD this weekend so hopefully can share more then. All i have right now is a pile of parts.
 

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Discussion Starter · #19 ·
Hi All,

I mentioned in my first post that the pile of parts were from a OEM prototype car that was built around 2012. When I bought the parts I was also given a lot of files inc CAN messages and block diagrams. I am currently looking through the files and discovered the below block diagram showing PDU HV connectivity so the CAN links are not shown but the inverter, charger, battery, and vehicle management unit (VMU) are. I have all the parts other than the VMU, and this is a problem as the throttle input goes from this VMU to the inverters. Do you think it would be too much of a challenge to develop a VMU of my own? I'm a mechanical engineer so pretty clueless with controls but I pick things up quickly. The other option is to reprogram the inverters to run on analogue input and not link the components through CAN but I will lose a lot of the functionality and safety features of the current design. What do you think?
 

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Discussion Starter · #21 ·
Given that there are separate left and right motors, I think it would be difficult to build a sufficiently capable control system, unless you have substantial ability to add programmed functionality to the motor controllers. For example, Curtis Instruments has controllers which are designed to be able to communicate and to coordinate control of two motors, so one takes the analog accelerator pedal input and serves as the control master, while the other controller gets its commands from the master and acts as a slave; each controller powers a motor. The intelligence needs to be somewhere, and if that's not the motor controllers I think you need a VMU.

Hi Brian, The Sevcon inverters are currently programmed to work in the same way, ie one is the master and the other is the slave. The master would have been receiving CAN messages from the VCU that it would decode and share with the slave inverter. Problem now is that I do not have the VCU so I will have to take the output from the throttle pedal, convert it to CAN messages that the Master inverter would understand. I would think you would have to do the same for any leaf inverter for example, so its possible, question is if i can do it with my limited knowledge. I have heard its possible to do this with Ardunio, and there is a lot of info on Ardunio on the net...
 

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Discussion Starter · #24 ·
Hi All, Been a while since i last posted. Having a child and building a workshop got in the way. Back to the project now.

I have taken the motors and built a temporary jig to hold the motors, they will be clamped to the bench which is pretty big and heavy.

The Sevon controller has the functionality to act as a master/slave, but it looks like the controllers were controlled independently by the old VMU. As the 1st phase of the test i'm going to try and get one motor to work by sending the correct signals to one sevcon. If that doesnt work then i need to get ahold of the DVT software (have the IXXAT USB to CAN already) and understand how the inverter has been programmed.

To get one sevcon working i'll need to build the pre-charge power circuit, 12v circuit, add F/N/D selector, accelerator pedal, and find 300V.

I have 150V in batteries from other projects, need to find another 150V!

Anyway, promise the posts will be more regular from now on!
 

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