Hybrid Integrated Propulsion POwertrain (HIPPO-2) Τest-bed
The Hybrid Integrated Propulsion Powertrain 2 (HIPPO-2) test-bed, seen below in Fig.1, consists of a 261 kW diesel engine connected to a 315 kW electric dynamometer (Brake). A 90 kW electric Motor/Generator, is attached at the free end of the dynamometer.
Fig. 1: The hybrid diesel-electric test-bed HIPPO-2 at LME.
The prime mover is a CATERPILLAR 6-cylinder, 9.3-liter diesel engine, with a rated power output of 261 kW at 1800-2200 rpm. The diesel engine is fitted with state of the art emission reduction technologies, an Exhaust Gas Recirculation (EGR) and a Selective Catalytic Reactor (SCR) NOx abatement systems. The electric motor/generator is a AC asynchronous-induction 3-phase motor, with a rated power of 90 kW. A frequency inverter unit enables the torque output regulation of the electric motor under closed loop control. The mechanical load is applied to the system through the electric dynamometer, which is a 315 kW AC asynchronous-induction 3-phase motor. In this setup, the thermal and electric engine provide mechanical power simultaneously, with identical rotational speeds. All the machines of the HIPPO-2 system can be operated either in torque- or speed-control mode.
The performance monitoring and evaluation of the hybrid system is performed with the various sensors that are installed in the testbed, as shown in Fig. 2. The whole testbed is controlled and monitored by a dSPACE MicroAutobox II controller board, programmed in the MATLAB/Simulink environment.
Fig. 2: Sensors, rapid prototyping and operator interface of LME/NTUA experimental facilities
During experimental testing various loading profiles can be applied. The mechanical load, applied by the dynamometer can simulate for example the vessel's propeller demand, with variable speed and torque, or a generator's loading profile with changing load at constant speed.
In low-speed operation and transient loading, the internal combustion engine has higher fuel consumption and produces higher emissions. During hybrid operation, the electric motor can assist the diesel engine, so as to meet up with the torque demand in a more optimum way.
In HIPPO-2 hybrid diesel-electric test-bed, various control methods are investigated in relation to the power split strategies, including optimal and predictive control methods. The control concept of the powertrain is presented in Fig. 3
Fig. 3: Control system allocation in HIPPO-2 system.