Tuesday, August 07, 2018

How the Gen 2 Volt Drivetrain (Really) Works

Is the Chevy Volt a parallel hybrid or serial?  Does the engine drive the wheels after the battery is depleted?  Or does it generate electricity to run the motors, like a range-extended EV?  There are tons of opinions about what class of hybrid the Chevy Volt fits into, and there is good reason for this. The truth of the matter is, it is all of these things and more.

If I have lost you, don't feel bad. After reviewing multiple sources of information about how the 2nd gen Volt works, it seemed to be something I would never get my head around (and still haven't).  Let me try to break down what I know and give you some valuable references.

Components of the Chevy Voltec Drive System

There are 5 main components involved in the Chevy Voltec drive:

  1. 1.5L ICE (Internal Combustion Engine)
  2. Electric Motor/Generator A (EMG A)
  3. Electric Motor/Generator B (EMG B)
  4. Planetary Gear A (PGA)
  5. Planetary Gear B (PGB)

How They Interact

The Planetary gear PGA is connected to EMG A and the ICE.  PGB is connected to EMG B. Both planetary gear sets are connected to the wheels, and they are connected to each other..  Together with clutches, they function as transmissions that switch and mix power from the engine, motor A, motor B, and to/from the wheels, into several possible configurations to maximize efficiency depending on the torque being demanded, charge state of the battery, and the speed of the vehicle.  It's really quite the mind-blow.  The bottom line is that, the configuration of the car can freely change from EV, to parallel hybrid, to series hybrid, and some interstitial stages having the properties of both at the same time - all seamlessly and within seconds of the previous.

For more information, check out this Youtube Video posted by Alex on Autos. It's very to-the-point and in-depth, but it does have some diagrams.

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