Initially work was performed to model the Flybrid Flywheel Module connected to a commercial vehicle driveline with hydraulic motor components and transmission components of varying levels of complexity. The vehicle model which had previously been validated with testing of a bus on Millbrook’s VTEC dyno was run over the standard LUB drive cycle to determine the fuel efficiency improvement that was possible for each of the hydraulic configurations. The initial results showed that either fuel efficiency improvements were not sufficient to hit the pay back targets, or the system had to be overly complex, which is not in-line with the objective to having a standard Flybrid Flywheel Module for multiple applications.
An alternative approach using an electrical system to connect the Flybrid Flywheel Module to the vehicle driveline was considered. The main concern with this approach was cost of the electrical system which consisted of two electric motors and their controllers. After consultation with a number of Tier 1 motor suppliers, it appeared that with the advent of mass produced electric cars, the cost of motors and their controllers was now at an acceptable cost point. An Electrically Connected Flybrid Flywheel Module Model was created and simulated with the vehicle model. After development of the control system and some optimisation of the strategy, Flybrid were able to demonstrate that use of the Electrically Connected Flybrid Flywheel Module has a potential fuel consumption improvement of >18% on a bus application. Additionally several methods of making further fuel savings were identified. Results also demonstrated that the flywheel connected motor generally operated close to the maximum efficiency point of the motor with the used strategy.
Discussion with Tier 1s on costs, OEMs on operating conditions for commercial vehicles and combining this with the expected fuel saving enabled the payback time to be determined. The result was a payback period of approximately 2 years which given Flybrid’s research is very attractive to OEMs and their customers.
The product appears to be at a very attractive price point, therefore the costs used are currently being verified and detailed discussion are being held with all major Tier1 electric motor manufacturers. Flybrid are also in the process of validating the concept to ensure that the performance predictions can be achieved.
These results are currently being disseminated to many commercial vehicle OEMs across Europe with expectation of generating interest in the system and making progress to developing a demonstrator system with a long term view on commercial production.
In parallel with this feasibility study, Flybrid have been evaluating other markets for the Flybrid Flywheel Module. This process has identified two additional market areas where the same system can be used to give significant additional benefits. The first market would be off-highway diesel electric powertrains, where a cost effective Electrically Connected Energy Storage Module can provide significant benefits by recovering kinetic energy, load levelling the engine load to improve engine efficiency or performance boosting to improve productivity. The second market is power generation where an electrical system can be used with electricity generator sets, to improve transient performance of the generator set, allowing the generator set to be optimally sized working at the best engine load without risk of any issues resulting from transient load steps. This also enables cleaner gas engines to replace diesel engines for many applications.
