Samenvatting

The aim of this report is to document the configuration, design and testing of an innovative hybrid electric weed brush to be carried by a Antonio Carraro SP5008 Hydrostaticly articulated multi-purpose maintenance tractor. This project is issued by Hissink Custom Made Machinery, as an graduate assingment for a 4thyear Automotive Engineering student at the Hogeschool van Arnhem & Nijmegen.The main goal of this assingment was to come up with the electrical configuration of a previously designed prototypeof the weed brush.Currently most of these weed brushes are driven by a hydraulic motor or via a PTO, resulting in poor efficiency and high noise pollution due to a high working speed of the internal combustion engine of the coupled tractor. By switching this driveline to an electric motor that is powered by an alternator in combination with a battery pack on the back of the tractor, the noise pollution can beseverly reduced due to a reduced engine speed of the tractor. This electric driveline also offers a higher effeciency compared to conventional driveline methods.The previously designed prototype consisted of solely the mechanical parts, including the frame, hydraulic and electric actuatorsto control the brush and arm, and an induction motor to drive the actual brush.To be able to control the weed brush from the driver seat of the coupled tractor, the electric actuators that control the tilt of the actual brush are controlled by using a joystick. This joystick is used to switch relays that control the extension and contraction of theseelectric actuators. The hydraulic actuators that control the sidewise swing of the arm of the weed brush are coupled to the existing hydraulic quick-couplings of the tractor, and can be controlled by using the existing joystick in the cabine of the tractor. Aflow control valve has been added to the hydraulic lines, in orderto limit the flow and make the control of these hydraulic actuators more preciseand manageable .The main driveline consists of a 48 [V] 5 [kW] three fase induction motor coupled to a high efficiency motor controller and fed by both a 225 [Ah] battery pack and a 100 [A] alternator. This motor drives the actual brush through a reduction gearbox in order to multiply the torque deliverd by the motorand reduce the speed of the actual brush to an allowable level of circa 300 [rpm]. It is controlled via a control panel located in the cabine of the coupled tractor, which allows the operator to switch on the machine, select the motor speed ranging from 0 to 2000 [rpm] (0 and 470 brush [rpm]) and monitor the state of the battery pack along with any occuring faults in the system.Coupled to the Power Take Off of the machine, is a 48-56 [V] 100 [A] alternator. This alternator allows the machine to operate in a hybrid mode, where the alternator is driven by the internal combustion engine of the tractor, to supply the induction motor with a current of 100 [A] at 48 [V]. Byincreasing the speed of this alternator, a voltage of 56 [V] can be reached. This voltage will allow the 48[V] battery pack to be charged when the induction motor is turned off or operates at very light duty. This alternator is driven through a gearbox in order to reach the desired speed needed for supplying the current and voltage to the induction motor,and for charging the battery pack. Using the machine in hybrid mode, will reduce the speed of the combustion engine to 1780 [rpm]. Compared to the engine speed of 2460 [rpm] when using a hydraulic or mechanical brush, a speed reduction of 27,64 [%] is obtained when using the brush in hybrid mode.This coincides with a noise reduction of 41 [%]. This drop in engine speed also offers a reduction in fuel consumption of 10 [g/kWh]. Using the brush in fully electric mode, to be solely fed by the battery pack, the engine speed is almost reduced to idle. Resulting in a speed reduction of 65,44 [%], coinciding with a noise reduction of 74 [%].Testing of the prototype has revealed that it is capable of competing with conventionaly driven weed brushes, yet offers asignificantlylower level of noise pollution, a reducedfuel consumptionand a higher efficiency. Thefore the recommendation is to domore extensive testing, tie up any loose ends and take the machine into production, in order to allow for smoother, quieter and greener weed removal.