Modeling and simulation of a diesel engine cranking system. Abstract This master thesis is a study of the starting system for a diesel engine and its components. Theories for each component were presented and models were derived for a complete starting system. Focus lied on the starter motor and the losses in the diesel engine, and the models were implemented in the simulation environment Saber. The starter motor model consists of a permanent magnet direct current (PMDC) motor with additional parts which complete the starter motor. The loss components in the engine were manly derived from theoretical equations but also by measured data. The components were used as building blocks and put together to the entire engine losses model. Measurements of the starting system were done and compared with the model’s simulation results for different temperatures. The simulated average engine speed is approximately 20 % less than the measured. iii Acknowledgement First of all we would like thank our supervisors Johan Hellsing and Tomas Johannesson and our examiners Torbjörn Thiringer and Jonas Fredriksson. Thanks to Axel Nicklasson, Christer Andersson and André Jennert at Synopsys for help with the modelling and Saber. We would also thank Mikael Räim and Kjell Österlund for help with the measurements. Thanks to Bertil Andersson and all the other helpful people at the engine department at Volvo Cars for giving their knowledge about engines and its friction. Also many thanks go to the people at the Electrical department at Volvo Cars and to the component owners and suppliers, especially Javier Bores from Bosch, for providing us with useful data. iv Contents CHAPTER 1...........................................................................................................................1 INTRODUCTION .................................................................................................................1 1.1 BACKGROUND.......................................................................................................1 1.2 OBJECTIVE ............................................................................................................1 1.3 METHODOLOGY ....................................................................................................2 1.4 THESIS OVERVIEW.................................................................................................2 1.5 OVERVIEW OF THE SIMULATION SOFTWARE ..........................................................2 CHAPTER 2...........................................................................................................................4 BATTERY AND CABLE .....................................................................................................4 2.1 INTRODUCTION......................................................................................................4 2.2 THEORY ................................................................................................................4 2.2.1 Battery .............................................................................................................4 2.2.2 Cable................................................................................................................7 CHAPTER 3...........................................................................................................................9 STARTER MOTOR..............................................................................................................9 3.1 OVERVIEW ............................................................................................................9 3.2 INTRODUCTION......................................................................................................9 3.3 DC MOTOR ............................................................................................................9 3.3.1 DC motor design..............................................................................................9 3.3.2 The principle of operation of DC motor ........................................................10 3.4 THE PERMANENT MAGNET MOTOR (PMDC MOTOR).............................................11 3.4.1 Permanent magnetic material........................................................................11 3.4.2 The advantages and characteristic of (PMdc motor) ....................................13 3.4.3 PM Motor with flux concentration.................................................................14 3.5 THE STARTER MOTOR ..........................................................................................16 3.5.1 Main circuit ...................................................................................................16 3.5.2 Planetary gear ...............................................................................................19 3.5.3 Solenoid switch ..............................................................................................20 3.5.4 Overrunning clutches.....................................................................................21 3.5.5 Operating of the starter motor.......................................................................18 3.6 TEMPERATURE DEPENDENCY ..............................................................................22 3.7 THE MODEL ........................................................................................................22 3.7.1 Effective Inertia .............................................................................................23 3.7.2 Starter characteristic .....................................................................................24 3.7.3 Ke and Kt.......................................................................................................26 3.7.4 Solenoid .........................................................................................................27 3.7.5 Starter Motor Inertia .....................................................................................28 3.7.6 Planetary (Internal) Gear..............................................................................28 v 3.7.7 Losses.............................................................................................................28 3.8 FUTURE WORK...............................................ERROR! BOOKMARK NOT DEFINED. CHAPTER 4.........................................................................................................................36 THE DIESEL ENGINE ......................................................................................................36 4.1 INTRODUCTION....................................................................................................36 4.2 THEORY ..............................................................................................................36 4.2.1 Mechanical losses in a diesel engine.............................................................38 4.3 MODELLING ENGINES ..........................................................................................40 4.3.1 Equations vs. Black Box.................................................................................40 4.3.2 Mean Value vs. In-Cycle Variation................................................................41 4.4 THE ENGINE MODEL.............................................................................................41 4.4.1 Loss components............................................................................................42 4.4.2 Model construction ........................................................................................50 4.4.3 Temperature dependence...............................................................................54 4.5 FURTHER WORK ..................................................................................................55 CHAPTER 5.........................................................................................................................56 STARTER SYSTEM...........................................................................................................56 5.1 THEORY ..............................................................................................................56 5.1.1 Engine starting requirement ..........................................................................56 5.1.2 Starting system design ...................................................................................57 5.1.3 The process of cranking.................................................................................58 5.2 MODEL................................................................................................................60 5.3 SIMULATION........................................................................................................60 5.3.1 Simulation achievement .................................................................................60 5.3.2 Simulation results ..........................................................................................61 CHAPTER 6.........................................................................................................................66 MEASUREMENTS.............................................................................................................66 6.1 INTRODUCTION....................................................................................................66 6.2 EQUIPMENT .........................................................................................................66 6.3 EXPERIMENTAL ...................................................................................................66