Sunday, October 1, 2017

2013 (Second Generation) Nissan Leaf Drive Unit Teardown

We recently came across a Nissan Leaf drive unit:

Not shown: CHAdeMO charger blob
and of course had to look inside.

First, some outside dimensions for reference:



The drive unit is highly integrated; for example, the motor phase connections are short busbars:



Removing the dozen-odd screws and the three terminal screws allows us to separate the inverter from the motor...


...resulting in a very strange-looking U-shaped motor.

Pulling the next dozen bolts holding the differential and gearbox to the motor separates the gearbox from the motor:



A few more shots of the motor:




The natural next step was to look inside the gearbox...


...which unfortunately meant draining a liter of suspicious red Nissan Leaf fluid out first.

After that, it was simple enough to remove yet another dozen screws and split the gearbox housing:


Nothing much to see here, standard single stage helical gear going into an open differential. More pictures:




Overall reduction is a little over 8:1.

Next we look inside the inverter. First, a quick look at the waterblock channels:


Nothing to see here, standard cast channels.

Cracking the power electronics enclosure open required breaking through a lot of RTV sealant...


...revealing the gorgeous (and never-before-seen!) innards:


The inverter is much less dense than we had anticipated; the IGBT's have their own module (rather than being brazed straight to the waterblock), and there is a lot of empty space over the PM.


Controller is unfortunately based around a datasheet-less Renesas microcontroller, as are all Japanese automotive electronics.

Capacitor is 1088uF, 600V, SH film:


And a lot smaller than the one inside the 2nd-gen Prius.

Few more shots, including gate drive power supplies:




Overall, very well integrated with few surprises. I would not even dream of reprogramming this inverter, as dialing in the motor tuning for something this large would be very involved. My one comment is that this motor is probably good for much more than 80KW peak - judging by its size I would venture to say it is a 200KW-class motor.

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