Hybrid LP/Electric Module Phase 2

The University of Kentucky in collaboration with Clark Material Handling has been testing different configurations of a hybrid module to enable electric drivetrain vehicles to utilize LP fuel as a power source. Market forces, regulations and developments in drivetrain technology are pushing the wider deployment of electric drivetrains and electric motors in mobile machinery. The hybrid module concept enables OEMs who have developed a simple electric propulsion system based on battery technology to quickly switch to LP as the ultimate power source. It could also enable aftermarket conversion. Our work on phase 1 of this development project is nearing completion. In phase 1, we tested several different components (traditional lead acid and thin-plate pure-lead (TPPL) batteries and permanent magnet (PM) and induction AC generators) for suitability. This testing enabled us to identify TPPL and PM as the preferred battery technology and generator technology respectively, tune engine operating parameters, and turn the module control logic, and adjust the design to account for commercial application concerns like sound levels, exhaust routing, and fuel tank placement. However, the phase 1 system was specifically created for experimenting with different components and to enable changes to the hybrid module operating logic. As such, it is not well optimized for general production. First, the module layout was designed to support all of the components with their different sizes and shapes without significant alterations to the frame. This resulted in wasted space and non-ideal placement of the engine, radiator and LP tank, and non-ideal routing of exhaust, coolant and fuel lines. The phase 1 engine/generator interface had to be highly customized to support space constraints of the various configurations, but this customized interface would not be supported by the engine manufacturer in full production. Similar adjustability issues with module control mean that the hybrid control module and the wiring harness are custom rather than production-grade and have been significantly modified during the project as we improved the design for safety, noise and operability concerns. Finally, the specific engine we are using, the Kubota WG972-L-E3, has reached the end of its EPA-permitted use. A commercial design will have to utilize a more recent engine model such as the WG972-L-E4. As we finalize the design, we will update all the components to the most recent models supported by the various suppliers. Specific items to improve include: 1) Select and specify the new engine and update design around its physical and electrical interface. 2) The placement of the major system components needs to be optimized for the desired TPPL design. 3) The wiring harness and module controller need to be finalized and ordered as production units. 4) The material handling and other target industries for this technology will require all components to be UL compliant, so the new design needs to be limited to only such components. 5) Design new adaptor plates for the engine. 6) To ensure the engine runs at maximum efficiency, the generator control program must be adjusted to continuously load the engine fully and to automatically reduce torque to prevent engine stall.