4 Wikipedia picture. Brushed DC-Machine. The 4 Quadrants. DC-motor torque characteristics. Brushless DC-Motor. Synchronous AC machines

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Vehicle Propulsion Systems Lecture 5 Hybrid Powertrains Part 2 Component Modeling Lars Eriksson Associate

Efficiency Maps Measured engine efficiency map Used very often 35 Engine efficiency map 3 25 Numerical values for

856,.81,.88} ā i v i h = {.11,.126,.86} Ē MVEG-95 A f c d 1.9 1 4 +mv cr 8.

Hybrid concepts Hybrid operating modes Example: Combined hybrid in power assist mode.

Classification Electric motors are often classified into four groups (there are other classifications) DC-Machines

1 Vehicle Propulsion Systems Lecture 5 Hybrid Powertrains Part 2 Component Modeling Lars Eriksson Associate Professor (Docent) Vehicular Systems Linköping University November 5, 21 Energy consumption for cycles Engine Efficiency Maps Measured engine efficiency map Used very often 35 Engine efficiency map 3 25 Numerical values for MVEG-95, ECE, EUDC air drag = 1 rolling resistance = 1 kinetic energy = 1 v 3 i h = {319, 82.9, 455} v i h = {.856,.81,.88} ā i v i h = {.11,.126,.86} Ē MVEG-95 A f c d mv cr mv 1 kj/1km Engine Torque [Nm] Engine Speed [rpm] Willans line approximation. Hybrid concepts Hybrid operating modes Example: Combined hybrid in power assist mode. Combined Hybrid Power assist mode E G PG T V Electric Parallel Combined Series Parallel S/A B P M Electric Motors Classification Electric motors are often classified into four groups (there are other classifications) DC-Machines Synchronous machines (sometimes including brushless DC-motor) Asynchronous machines Reluctance machines There are also other devices: Stepper motors (Digitally controlled Synchronous Machine), Ultrasonic motors.

The 4 Quadrants Brushed DC-Machine T Brush-type DC motor: Rotor 2 Braking Driving 3 1 Driving Braking 4 ω Wikipedia picture Stator Commutator Two subtypes: Permanent magnet Separately excited Pros

Replace electromagnet in rotor with permanent magnet. Rotate field in stator.

2 The 4 Quadrants Brushed DC-Machine T Brush-type DC motor: Rotor 2 Braking Driving 3 1 Driving Braking 4 ω Wikipedia picture Stator Commutator Two subtypes: Permanent magnet Separately excited Pros and cons + Simple to control Brushes require maintenance DC-motor torque characteristics Brushless DC-Motor Characteristics of a separately excited DC-motor Solves DC commutator and brushes problem Replace electromagnet in rotor with permanent magnet. Rotate field in stator. DC-motor is misleading DC source as input Electronically controlled commutation system AC Linear relations between current and torque voltage and rpm Synchronous AC machines Torque Characteristics AC machine Rotor follows the rotation of the magnetic field Has often permanent magnets in rotor This is the same as the brushless DC motor. Brushless DC Asynchronous AC machines Induction motors Stator has a rotating magnetic fiels Rotor has a set of windings, squirrel cage See separate animation. Electric field induces a current in the windings Torque production depends on slip. Torque Characteristics Induction AC motor

3 Reluctance machines Reluctance = Magnetic resistance. Synchronous machine Rotating field Magnetic material in the rotor Rotor tries to minimize the reluctance Motor Modeling Quasistatic (equations are general) Power relationships: input power P 1 (t) delivered power P 2 (t) = T 2 (t) ω 2 (t) Efficiency usage P 1 (t) = P 2 (t)/η m (ω 2 (t), T 2 ), P 2 (t) > P 1 (t) = P 2 (t) η m (ω 2 (t), T 2 ), P 2 (t) < Description of the efficiency in look-up tables Willans line to capture low power performance First quadrant maps for η m AC machines PM Synchronous Extending the Maps for η m Traditional first quadrant drive is normally well documented Supplier information for η m ( ) Electric motor drive P 2 (t) = η m (ω 2 (t), T 2 ) P 1 (t), P 2 (t) > Electric generator load P 1 (t) = η g (ω 2 (t), T 2 ) P 2 (t), P 2 (t) < How to determine η g? Method 1: Mirror the efficiency map η m (ω 2 (t), T 2 ) = η g (ω 2 (t), T 2 ) Induction motor, Asynchronous AC Method 2: Calculate the power losses and mirror them Method 3: Willans approach Two Quadrant Maps for η m Motor Modeling More advanced models Use component knowledge: Inductance, resistance Build physical models Dynamic models are developed in the book. Mirroring efficiency is not always sufficient. Electrical Machines in Hybrids Machines encountered Separately excited DC Permanent magnet synchronous DC Induction motors (Switched reluctance machines) Considered to be interesting AC motors (compared to DC motors) Less expensive but more sophisticated control electronics, gives higher overall cost. Higher power density, higher efficiency. AC motors (permanent magnet vs induction motors) Averaged values from Advisor database. Efficiency Power density permanent magnet 92.5 %.66 kw/kg induction motors 9.5 %.76 kw/kg

4 Batteries Modeling in QSS Framework Energy storage devices Energy density important Performance Power density important Durability Causality for Battery models in QSS. P 2 PA BT Q Energy Power cycles Battery type Wh/kg W/kg Lead-acid Nickel-cadmium Nickel-metal hydride Lithium-ion Models have two components The first component is = P 2 The other, the relation between voltage and terminal current SOC = f (SOC,,...) Standard model Voltage and SOC Simple model for the battery Open circuit voltage U oc R i Uoc Output voltage = U oc R i Battery Efficiency definition Efficiency definition is problematic Not an energy converter Energy storage Peukert test Constant current during charge and discharge. Ragone test Constant power during charge and discharge. Efficiency will depend on the cycle. Efficiency definition Instantaneous E d = E c = tf tf P 2 (t)dt = /Peukert test.../ = t f (U oc R i ) P 2 (t) dt = /Peukert test.../ = t f (U oc +R i ) η b = E d E c Can also define an instantaneous efficiency. Supercapacitors Supercapacitors and ultracapacitors High power density Used as short time scale energy buffer. Load leveling to the battery. Very similar to battery in modeling Exchange the battery for a capacitor in the circuit below. R i Uoc Efficiency definitions Peukert and Ragone

Power Links Electrical glue components DC-DC converters DC-AC converter Account for power losses Torque couplers Components that are included to: Glue for mechanical systems acting on the same shaft

5 Power Links Electrical glue components DC-DC converters DC-AC converter Account for power losses Torque couplers Components that are included to: Glue for mechanical systems acting on the same shaft Can include: Gears in the coupling equation Sub models for friction losses Basic equations Angular velocities Torque (from a power balance, including losses) Power Split Devices Manage power splits between different components Important component for achieving flexibility Modeling approach: Speed relations with torque from power balance. Can add more planetary gears

Vehicle Propulsion Systems Lecture 4. Outline. The Vehicle Motion Equation. Energy consumption for cycles. Engine Efficiency Maps.

Vehicle Propulsion Systems Lecture 4. Outline. The Vehicle Motion Equation. Energy consumption for cycles. Engine Efficiency Maps. ehicle ropulsion Systems Lecture 4 Hybrid owertrains, Topologies and Component Lars riksson rofessor ehicular Systems Linköping University arch 23, 2018 2 / 64 2 / 64 Introduction to Hybrid-lectric ehicles