Hydraix I

High efficient urban concept fuel cell vehicle prototype

Our competitor for the “Eco-marathon” 2023

The idea of this project is to build a concept car, that is reduced on main specifications and could suit urban driving mobility needs for one person. This vehicle was designed to consume as little energy as necessary. In addition to specially designed system components, a digital driving strategy has been developed to optimize driving performance on the track. For further optimization, supercapacitors were added to the system to provide temporary energy storage.

Quick facts:

weigth: 110 kg
max speed: 40 km/h
energy conversion trough 1 kW air cooled PEM fuel cell
consumption rate: 83.3 g/100km
motor power: 2 x 380 W

Big step up from Charlemagne

weigth: 225 kg
max speed: 55 km/h
energy conversion trough 3 kW liquid cooled PEM fuel cell
consumption rate: 374 g/100km
motor power: 2 x 1 kW

Vehicle highlights

Carbon Chassis as the Base

As a foundation, we simulated a chassis optimized for our specific requirements and loads out of different materials. Our choice was a carbon foam sandwich material. Attached to this chassis are all the further components of the car, such as the wheel suspension, steering, electrical system, and the fuel cell system. The modular design of our vehicle allows for easy maintenance and upgrades.

Carbon Aeroshell with Minimal Drag

To minimize drag, our vehicle’s design is refined through aerodynamic simulations. The manufacturing process, carried out entirely in-house, involves milling molds from epoxy blocks, followed by glass fiber layup for creating a precise negative tool, and finally, a carbon layup for the structure. This process is divided between two molds for the upper and lower parts, streamlining production and ensuring a high-quality finish, underscoring our commitment to innovation and efficiency.

High Efficient Motor and Transmission

Equipped with dual 280W motors, our drivetrain has an efficiency of over 90%, aiming for minimal energy consumption. The inclusion of a 2-stage gear transmission optimizes speed and torque to the ideal top speed of 40kmh. Additionally, we manufactured topology optimized rims for the competition wheels.

Fuelcell system

Hydraix is equipped with an 1kW air cooled fuelcell that uses hydrogen and oxygen to generate the needed electrical power. The whole system includes lightweight components such as valves, pressure reducer and PTFE pipes, and is mounted in a carbon frame. Multiple sensors provide details about the current state of the system and gives feedback to the control strategy.

Electric System

For efficiency optimization and temporary energy storage we use a block of supercapacitors, these components allow very quick charging rate. The key to this system is to use as much energy as possible directly from the fuel cell. This path of power electronics ends in two electric motors.

Controlling and Driving Strategy

This system integrates a 1 kW air cooled fuel cell into a directly controllable hybrid system.

The fuelcell system in 3D

In-house Developments Highlights

Atava

Atava is a C++, freeRTOS based rapid prototyping system and forms the software of Hydraix. It is developed in a way that every hardware component can be individually implemented in a RTOS taks and tested without the rest of the system. Atava also makes CAN Bus communication, data logging and data injection during testing, easy. Every controller of Hydraix runs Atava as the base system and on top the individual hardware controlling and processing. Additionally, the main controller runs a compiled Simulink model, that interacts with all other controllers and acts as the control and driving strategy. Atava also natively implements an emergency mode which can be triggered and safely stops the whole system.

Control Hardware

Hydraix I has two control units. The Bus Interface and the Main Controller.
In order to streamline the PCB design process, commonly required functions such as DCDC converters, Can communication, power measurement or a microcontroller have been incorporated into the Bus Interface.
Hydraix I contains a total of 3 Bus Interfaces with different self designed shield PCBs.
The heart of the control system is our main controller, which uses a Teensy 4.1 to run our strategy, controls all the other Bus Interfaces via CAN and directly controls our power system.
It also allows easy debugging, either via the display or by connecting a CAN module to it.

Hybrid Supercaps System

To balance out peaks and valleys in power demand, we developed a system that is capable of storing energy in super-capacitors and consequently releasing it. Combining the two energy sources takes a bit of effort in controlling, which we developed detailed models and strategies for. This makes Hydraix a hybrid vehicle.

Steering Wheel

Our steering wheel is more than just a part that steers our car. With the steering wheel, you are able to control all the settings that are needed to drive the car on the track. You set the throttle, activate / deactivate the manual or automatic driving mode, control all the lights and see the actual energy of our supercapacitors. You will also see the load that is provided by the fuel cell itself.

To achieve all that, we had to build our steering wheel completely by ourselves. The main structural part is a carbon backplate that gives excellent stability. On top of that is our 3D-printed cover, which holds the LCD and the required buttons. Our throttle is placed on the back for ergonomic handling while driving. All the signals come together in a self build printed circuit board, which then transmits the data to the other hardware components.