Various types of dc motors for traction application

i am doing a research on which motor is better suited for Small EV or kart conversion using a fixed gear (single stage).

the options available are : PMDC , SepEx , Series , BLDC . ( No ac motors )

I have found so many information regarding BLDC motors and their advantages , but no useful info on the other types .

So assume 4 motors of each type that can rated continuously (S2 duty) to work on 96v 100A , what which motor is better for traction ? my initial guess is Series or SepEx , since you can design the fixed ratio gearbox for maximum torque required (hills). and get extra speed when torque is not needed (flat road) by "Field Weakening" ( something like electrical gearing) . while with PMDC or BLDC you cannot do that .

1-is my logic correct ?
2- what are the criteria in choosing one of these motors ?
3- how much you can weaken the field and how much extra speed you will get (to stay in safe zone) , most motors shops donot provide much scientific information for an engineering or academic approach .

BLDC are actually AC motors (in sheep's clothing) and you control the speed and torque by changing the frequency and voltage together in accordance to some graphs.

PMDC are the simplest to regulate. I see you are going to use a 10 kW motor. Of course you can regulate the torque and speed of PMDC motors- it is one of the simplest. You can also control the torque and speed of BLDC motors but the regulator is far more complex.

Series motors can also be speed /torque regulated but within a narrower range.

There is a reason that series-wound DC motors *were* very popular as traction motors for locomotives and tramways.
And that is because of its torque/speed characteristics.

However with the advent of power electronics, they now use low-slip AC induction motors coupled to variable frequency drives.

But to your project: I second c-mitra's suggestion: a PMDC is by far the simplest to control. The only thing to watch out is that you have a to limit the maximum allowable armature current. For any stall or overload condition.