Project target -> find best POWER to COSTS compromise


Max power: 6600 Watts
Weight: 32.00 kg
Battery setup: Lipo 8 x 7s x 4000 mAh (~60 Volt - 16000 mAh )
Max motor current: 150 A (400 A peak )
Max speed: 60 km/h ( limited by the bike frame stability )
Max torque: very high, limited by the bike frame
Throttle: half turn hall throttle
Electronic control type: Turningy Dlux 250A + custom controller
PWM Frequency: ~ 10 kHz ( still audible )
Bike frame: BTwin Rockrider 500 size L

The story

We built this ebike because someone asked us to build one ... so we accept because we were interested in creating new custom BLDC controller with smart capabilities and most of all we didn't look forward to ride it during the tests!

At the beginning this project seemed not too complicated, we had only to put a motor on a bike ... but that was not true !!! The customer requests were a fast and powerful e-bike, a heavy duty structure that should carry him up the hill for a great distance and most of all with a budget as low as possible. Now the things went difficult.

As you can see looking at the YouTube video, the job was pretty long, lots of tries and for every failure we searched for a solution. Now the e-bike is working, every time better than before, and we continue to improve it ahahah an ever ending story!

I want to share some details of the BLDC controller, realised from scratch, to meet the high current requirements and safe operation.

The BLDC custom controller development

At the first attempt we use a commercial electronic speed controller (ESC) from the hobby market, but this type of product is not designed for automotive purposes, as not current loop for torque control, just open loop speed regulation, no matter the load, the bike was moving at the throttle set speed... during the first test we broke some bike chains and the feeling was like riding a loaded catapult ready to fire at the first wrist move ahahah not very comfortable. So lets create a new controller!

We started trying to move an old floppy disk bldc motor, at the heart of the controlled there's the Atmel Xmega micro controller, a very features reach micro that runs at 32MHz, it's still a 8/16 bit arch but is powerful enough for our needs.

So I began to study the micro peripherals, the ASF (Atmel Software Framework) and after few nights I developed a working firmware!