Development of a small scale hybrid wheel loader test platform
Examensarbete för masterexamen
Björe Dahl, Per
For construction equipment in general fuel efficiency is one of the most critical product attributes. Pure fuel economy improvements from the engines are extremely expensive to develop. This creates an incitement for development of hybrid technology. This thesis was done in corporation with CPAC Systems in Gothenburg, Sweden. With regenerative braking, the energy that is normally transferred into heat during braking can be stored in a battery or a super capacitor and the stored energy can later be used for propulsion. However the regenerative braking also affects the vehicle dynamics and the driver’s interpretation of the brake pedal which demands for a physical test platform for testing. In this thesis a test platform for testing of concepts was developed and built and a brake blending system was developed and tested on the test platform. The test platform was built in small scale compared to a full wheel loader with an articulated rideable lawn mower as base. A small scale test platform has the benefits of fast and easy testing and much lower cost compared to a full scale wheel loader. The test platform is equipped with individual wheel motors and a mechanical brake system based on brakes from a motorcycle. The first step in the development of the control system for the test platform was to make Simulink models for the components in the test platform. Models for the overall vehicle, the brakes and the electrical motors were developed. From the models a control strategy was developed to control the requested torque to the electric motors and the requested brake pressure to the brakes from the driver’s inputs. The control strategy was developed in Simulink and from Simulink C-code was automatically generated by the code generation tool TargetLink. All testing including testing of the brake blending system was performed on the test platform. The result of this thesis is a test platform that is built to emulate a small scale hybrid wheel loader. The test platform is expandable and can be used to test other concepts, for example steer-by-wire. The other result of the thesis is a brake blending system that is combining electrical and mechanical braking with good pedal feeling, no wheel lock and high energy regeneration.
Elektroteknik och elektronik , Electrical Engineering, Electronic Engineering, Information Engineering