|Engine Power:||2 x 50 kW|
|Acceleration (0-100 km/h):||< 3.0 sec|
|Maximum Velocity:||130 km/h|
The electrical systems subteam is responsible for all the components in the car which relate to power and voltage. To this end, they integrate all circuit boards, the low and high voltage cable harnesses, the programming, the sensors, and the safety circuit in the car. Alongside that they also work on the whole tractive system, which is composed of the accumulator, AC converter and motors. The electrical components also helped to build on the experience from the previous car, Murph-E. During the transfer to the new car, KatE, the focus was placed strongly on the components which exhibited potential for improvement in Murph-E. Components which already functioned well were further developed for better efficiency and reliability.
Electrical specifications of KatE:
- 2 brushless synchronous motors Siemens 1FE1064
- max. power: 50 kW
- max. torque: 105 Nm
- max. revolutions: 8000 rpm (electronically limited)
- 2 Siemens inverters SINAMICS S120
- max. output current: 141 A (RMS)
- max. output voltage: 480 VAC (RMS)
- max. voltage: 600 V DC
- total energy: 5,3 kWh
- 288 lithium-polymer pouch cells with 144s2p interconnection
- nominal voltage: 3,7 V
- capacity: 5 Ah
- max. continuous current: 275 A
- complex, self developed battery management system
- DC/DC converter to power the 24 V electrical system
- wheel speed sensors
- steering angle sensors
- travel sensors
- coolant temperatur sensors
- brake discs temperature sensor
- tyre temperature sensor
- SmartSensor-approach for direct conversion of the sensor data to the CAN-bus
- Single Board RIO from National Instruments
- Vehicle software implemented with LabView
- Recuperation, electronic differential, traction control, torque vectoring
- CAN-buses to the on-board communication
- WLAN for real-time telemetry logging
Aside from that, the module is responsible for electrical safety. The development and supervision of safety measures ensures all team members are able to work with the electric car and its high voltage components in a hazard-free environment.
Frame and Body
Becoming an integral part of Elbflorace in the last years, the selfsupporting chassis (monocoque) in its fifth version is manufactured out of pre-coated carbon-fiber mats using the autoclave-process.
Our priority this season was the improvement of the layer-construction and the level of lightweight-construction. Again we where able to save approx. 2 kg. Using a new joining method for the adhesive joint was one of our major interests.
Alongside the monocoque our module has focussed on the following essential subject areas:
Implementation of aerodynamic aspects
- intensive use of universities know how
- Use of underfloor
- Aerodynamically optimised design of the nose and side pods
- Design of the steering rack cover to level out with the monocoque layers
- Distinguish between structural and non-structural parts
- Optimisation of the crash element
- New method for the firewall plate (also to simplify the manufacture cost)
- Use of a shoulder harness bar
- Adjustable pedals including heel guidance and a lateral support for the driver
- More space for the driver’s legs
- Upright sitting position with higher stiffness in the sides of the seat for stability in the corners
- Use of a cushion for short drivers
- Adjustable head-restraint
- Rail-System for the battery case
- use of a pedal mount
- Clear arrangement and accessibility of all pedal box parts
- Re-use of the cover concept for the motor
- LEO-system for the firewall und battery case for fire protection
- local strength improvement of the laminate-structure for the harness attachment-point
Putting the potential (electrical energy) in kinetic form on the road is the responsibility of the powertrain module.
Comprising the divisions gearbox, drive shaft and cooling, they are the link between electrical subsystems and suspension.
The gearbox was based on the existing concept from Murph-E, since the general set up of the motors was the same. During the transfer particular attention was paid to failures of the last season, and above all to the maintainability, so that the assembly in the car could be simplified and sped up. The transmission wheel was connected directly to the engine gear wheel in order to obtain the best possible sensor signal and improved access to the motor shaft-gear connection. The gear ratio was also changed from 4.6 to 5.8 to improve the acceleration. This was also done so a better motor efficiency could be achieved because the increased stress was spread across a wider field. During the design of the gearbox housing the main focus lay on simplifying the manufacturing process, to enable the shortest possible build time and stick to the tight schedule.
The concept of the last season could also be reused, but choosing a new high strenght steel reduces weight and the number of parts drastically.
We have chosen a complete diffrent way in terms of cooling: two cooling circuits instead of one, smaller hose diameter, stronger and yet smaller water pumps, lower volumetric flow rate, and a modular design. The coolers are mounted in front of the main roll hoop,in order to enable improved airflow and thus cooling efficiency along with the aerodynamically designed side pods. Due to the modular nature of it, the cooling circuits can always be changed, so we can test out different cooling circuit layouts.
KatE’s suspension was largely similar to Murph-E, which amongst other things was due to the use of the same monocoque. We corrected many of the failures and problems from the previous season’s design, but parts which had worked well were just worked on with weight optimisation and manufacture in mind. The hub kinematics were completely redesigned. For example the vertical dampers on the front axle are triggered by pull-rods and on the rear axle by push-rods. The design allowed us an effectively lossless wheel deflection and so a good performance on track. Some technical information:
Tyres and rims:
- Continental 205/510 R13
- Braid 6,5×13 central lock
Spring / damper / anti-roll bar
- ZF dampers connected to H&R racing springs
- Sword-type anti-roll bar
- ISR calipers – 4 pistons at the front, 2 pistons at the back
- Self-developed steel discs
- Adjustable brake balance
- progressive steering gear box from PSS
- adjustable steering column holder
- Carbon fibre tubes with aluminium inserts
- Injection adhesive technology for high reliability
- High strength aluminium
- Manufactured on a 5-axis mill, topology optimised
- Geared camber setting
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Design lighter, low noise transmissions. Our software makes it possible.
Entwicklung und Fertigung Eßbach GmbH & Co. KG
Development and production Eßbach GmbH & Co. KG - Always an idea cooler! The specialist for liquid coolers, heat exchangers and peripherals.
Vector Consulting Services GmbH
Vector suppports the development of automobile electronics. We offer a platform of tools, software components and services for developing embedded systems.
Bürklin Elektronik is a classic distributor for high-quality electronic components. We serve our customers from the prototype to the series.
At this point of the season we validate our construction by simulating all parts. This is necessary to detect errors before we actual produce our car. Better be safe then sorry. We set up FEM- simulations for every part in the car. Thanks to ANSYS the process therefore is very simple but still reliable. With ANSYS we can be sure that even our most complicated parts don’t break on the race track.
Bender GmbH & Co. KG
Optimized insulation monitoring within the smallest space – the Bender ISOMETER® IR155-3204 is perfectly tailored to electro and hybrid vehicles.
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