Motor Control Unit (MCU) Details

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kiev

Well-known member
Joined
May 3, 2015
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The Heart o' Dixie
Also known as a motor drive inverter, here are some photos and details of the internal components. Thanks to Ben Nelson for making some utube videos of his ordeal with a saltwatered miev as i bootleg his photos.

Here is a view from the top of the upper chamber with the high power components, where you can see the black, white and red motor phase terminals and the main pack HV lines with + closest to the red phase and - on the right. The black plastic cover thing is a large ShiZuki 800uF 450 VDC capacitor, aka condenser.
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Here is a view of a crusty crab control board located in the bikini bottom chamber below the liquid-cooled heatsink. The MCU recall is likely due to some component on this board.

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Here you can see 2 Nippon Ceramics Co current sensors on the buss bars (1.5mm, 0.060" thick) of the black and red motor phases. The white rectangular device at the right is a 56 kOhm power resistor to bleed the high voltage from the condenser after the key is switched off, which will take about a minute. A couple of other HV lines are fed off the main pack buss bars (one has an inline fuse ??, one is a small sense line).

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This is the business end of the three phase bridge that switches and routes current thru the motor. There are 3 boards located below the condenser and attached to the Hitachi 600A/600V IGBTs (MBM600JU6B). Four wires to each board, 2 for the top and 2 for the bottom gate drivers, so an aftermarket hotrodder could tie in here to drive the motor with something like a custom arduino controller...

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These seem to be compact well-designed motor controllers with plenty of margin in the high power components. They could easily be repaired if necessary and if the replacement components could be sourced.
 
Thanks for these captures.

I wonder if those smaller screws on the HV lines could be accessed and used to tap into the pack voltage for external charger and/or pack through the small access panel?

This way there wouldn't be a need to take the whole lid off along with it's seal, which might break in the process, not to mention voiding any warranty. The small access panel I'm thinking of replacing with a piece of sheet metal, so I can keep the original intact and still make a couple of holes into the panel to get cables through.
 
Making a small cover with access holes sounds like a good idea. Needs a good tight grommet or gland seal because there is lots of dirt and silt thrown up in that area in addition to possible splashing rain water.

There are no interlocks or void-warranty labels on the lid(s) such as tesla uses. The only security devices are single Torx screws in each cover. For the access cover you would need a 10mm socket and a Torx 30 for removal. The main lid needs 8mm socket and Torx 25.

The small cover just has a rubber gasket and pops right off, but the lid is glued on with a very thin layer of gray-colored sealant that requires the use of an M6 jack screw to break the sealant joint.

The access cover would let you get to the main terminal DC buss bars, but there is no voltage on them unless the internal relays in the pack are energized such as when the key is switched to ready. They had no voltage in just the 'acc' or 'on' positions. There is voltage on the buss bars for a couple of minutes after powering off as the condenser bleeds down.

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i would have added this to the first post, but editing is not allowed on old posts for some stupid reason,
picture of the internal circuits of an IGBT
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