I recently bought a Kia Ceed 2020 PHEV (Plug-in Hybrid Electric Vehicle). Its specs mention a 6-gear Dual-Clutch Transmission (DCT), a 105 kW Internal Combustion Engine (ICE) and a 44 kW Motor-Generator (MG). The user manual mentions a Hybrid Starter-Generator (HSG).

I'm struggling to understand how all these components are connected and how they transfer power in some modes. There are plenty of YouTube videos describing the Toyota hybrid drive train, but I didn't manage to find anything that describes a drive train with a DCT -- except some rather uninformative marketing videos.

In particular, the car seems to like turning on the ICE for cabin heating, even if propulsion is completely electric. In this mode, the ICE seems to run at constant RPM and charge the high-voltage battery for additional load and better energy conservation. This suggests two separate "paths" for the high-voltage battery to be charged mechanically, one from the wheels and one from the ICE.

I tried "reverse engineering" the drive train in the diagram below, based on marketing material and my observation that the MG seems to be connected through the DCT to the wheels. I highlighted more "hypothetical" components with a question mark.

Hypothetical PHEV Drivetrain


  1. Does this arrangement make sense?
  2. Can the HSG charge the high-voltage battery?
  3. Is there a clutch between the ICE and the MG?

1 Answer 1

  1. Yes but it's not likely to be fully representative. If I were doing it, ? would be an integrated charging circuit around the 12V that includes the HSG and the inverter converter since it also charges the 12V off the ICE through the G of the HSG. The DCT might be something else as well (see 3)
  2. Not likely. the MG is specifically for that. Again if I were doing it, the HSG+ item in 1 would have the job to charge and maintain that 12V.
  3. Possibly, but if there is a DCT, it's probably the DCT. ICE, MG, and Differential would connect to DCT. DCT would be able to engage or disengage both ICE and MG from the Differential driveshaft. Rather than a clutch, there may be an alternate mechanism to vary the effect of the MG - such as powered coils instead of or in addition to permanent magnets, or better yet- a gearshift?

Engaging just the MG would allow the HVB to power the DT and also allow regenerative braking to charge the HVB. Engaging just the ICE would allow the heating of the cabin while preventing charging to continue on a fully charged HVB. Engaging both allows ICE to drive and charge HVB. Engaging neither lets you go into neutral and tow or push a vehicle.

  • $\begingroup$ Thanks for the answer! Can you also explain, if the DCT is the DCT, then how does the ICE charge the HVB, without going through the MG? In cold mornings, the ICE heats the cabin and charges the battery, but without driving the DT. $\endgroup$ Sep 19, 2021 at 12:00
  • $\begingroup$ consider what happens when the vehicle brakes. Think of an additional interface that allows the wheels (DT) to be stopped while the engine continues to turn. Can think of it as the output of the DCT, but specifics would need more intimate knowledge than I have. Rather than waste the ICE when wheels are stopped, it's great to send that energy to the HVB- hence why the combined ICE and MG take the place of the normal vehicle ICE. $\endgroup$
    – Abel
    Sep 19, 2021 at 20:56

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