rfguy
Posts: 7
Joined: Sat Jul 29, 2017 11:45 pm

Drive range questions

Fri Feb 01, 2019 9:52 pm

I recently watched a very cool you tube video from Weber Sate University called a deep dive into chevy bolt drive unit. One of things I was curious about that was not covered is what happens in L range and R range. I have a theory that reverse is accomplished in the single power 3 phase inverter where any 2 phases are reversed via a contactor which would reverse motor rotation. I would like to know if this is true or not. Also I would like to know how L range increases the regenerative braking. In town we always drive in L range as the service brakes are not needed as long as the battery is not fully charged. Thanks for any comments.

WetEV
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Posts: 377
Joined: Sun Jan 03, 2016 1:26 pm
Location: Near Seattle

Re: Drive range questions

Sat Feb 02, 2019 2:39 am

rfguy wrote:I recently watched a very cool you tube video from Weber Sate University called a deep dive into chevy bolt drive unit. One of things I was curious about that was not covered is what happens in L range and R range. I have a theory that reverse is accomplished in the single power 3 phase inverter where any 2 phases are reversed via a contactor which would reverse motor rotation. I would like to know if this is true or not. Also I would like to know how L range increases the regenerative braking. In town we always drive in L range as the service brakes are not needed as long as the battery is not fully charged. Thanks for any comments.


The motor is 6 phase, and is computer controlled. The computer will energize phases, one at a time, to make the car move. If the computer energizes 1,2,3,4,5,6,1,2,3,4,5,6,... the car goes forwards. If the computer energizes 1,6,5,4,3,2,1,6,5,4,3,2,1,... the car goes backwards. If the phases are moving at the same speed as the car, there is no acceleration or braking. If the phases move slower, the motor brakes the car. "L range" is just a software command to the computer to tell it to work harder slowing the car.
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SeanNelson
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Joined: Tue Jul 05, 2016 2:43 am
Location: Vancouver, BC

Re: Drive range questions

Sat Feb 02, 2019 6:25 am

WetEV wrote:
rfguy wrote:The motor is 6 phase, and is computer controlled. The computer will energize phases, one at a time, to make the car move. If the computer energizes 1,2,3,4,5,6,1,2,3,4,5,6,... the car goes forwards. If the computer energizes 1,6,5,4,3,2,1,6,5,4,3,2,1,... the car goes backwards.

Exactly. There are no gears to change, and no contactors to open or close. It's not a DC motor where the current needs to be reversed in order to switch directions, it's an AC motor where motor speed and direction are controlled by the timing and strength of the current being applied to the various coils.

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