Switch to AC induction motor

Post date: Aug 15, 2014 9:35:39 AM

After the first testdrive, we were disappointed with the KellyController/ME0913 combination. One of the controllers kept tripping despite not even drawing its nominal current. Probably its specs are overrated. We also had a slight wobble in the rotor discs, which creates a wirring noise during driving.

Eventually, the decision was made to switch to a more powerful motor/controller combination and we stumbled upon the conversions of Heiko Fleck, from whom we sourced a rewired AC induction motor from Schwarz Elektromotoren. It is rated at 70kW peak, and we will be using it with a Curtis 1238-7601 controller. It can provide up to 650A to the motor at 100V.

Rewound AC induction motor 40kW/70kWp arrived. It's quite heavy, at about 70 kg.

Picture of the motor as delivered. It is quite difficult to move, at about 70kg... Also, the connection box on top makes it impossible to fit batteries above the motor. Therefore we had to carefully change the motor wiring.

Replacing the leads of the motor so that the connection box on the top can be omitted. Height is critical.

Eventually, a new adapter plate, spacer and coupling for the flywheel was drawn in Autodesk Inventor. The bolt patterns were then drilled using a CNC mill in a used piece of aluminium:

Finished adapter plate, spacer and flywheel coupling. The latter's diameter was made about 0.1-2mm too small so that it would fit after heating to 200C.

Clutch bolted on, ready to locate the motor onto the gearbox. We did not know if it would fit exactly at this point. At some corners only a few mm's of margin are expected.

Eventually it was time to put the motor inside the car. Because the space was so limited, the gearbox had to be moved by about 2cm to make the motor clear the steering rack. There would not be enough space to put batteries above the motor anymore...

Eventually, a slot was cut into the cooling fins on the bottom of the motor to be able to lower it some more.

Conveniently, the winch that was tied on the roof of the garage broke just when the motor was in position... We cannot get it out anymore for now.

Motor on gearbox. Piece of cake. ... Well okay we did need that hammer. Also, the gearbox had to be relocated about 2cm higher.

The front battery box also serves as a mounting point for the Curtis motor controller. In the picture below, the HV cables from the rear battery box were already installed as well.

The HV wires are required to be orange, so that emergency services can identify them quickly. Since these cables run alongside the transmission tunnel on the bottom of the car, we wanted some additional protection. Thus the cable is pulled through transparant hose: