Effective
th x Q x mech

• th = thermal
• Q = quality grade
• mechanical efficiency
  
  

Q = ge x b

• ge = efficiency index (graph/graph)
• b = rate of complete combustion (fuel conversion factor)

Injection of fuel, compression of mixture -> uncontrolled self ignition due to overpressure. The self ignition creates pressure peaks creating a shock wave -> knocking/rattling. This can damage the material It's more obvious in winter & low temperature, high ignition delay

Process:Intake of air and injection of fuel. Homogeneous mixture of air and fuel. Spark plug burns/ignition

Knocking
If self-ignition happens before flame front -> rapid combustion happen with new higher temp and pressure -> knocking f(fuel, form of combustion chamber)

Counter measures:
ENGINE: short flame travel, charge air cooling in turbocharged engines, spark plug in hottest place, limit compression ratio
FUEL: high ignition delay with high alkenes or benzene ratio or anti-knocking solutions

Alcohol

• Engine: similar to gasoline with high compression or diesel with spark ignition
• Most relevant fuels:
  -- methanol CH4O: 37% less CO2 if produced with natural gas, 100% if with coal
  --ethanol C2H6O: production from biomass, low quantities
  
  
  

- PROS:
-- clean cumbustion,
-- better efficiency due to high compression
- CONS:
-- low heat value, which requires more fuel to have the same output power compared to gasoline and diesel, therefore the tanks are bigger and require more space
-- Aggressive agains metal, rubber and plastic
-- Poor cold start properties
-- Availability limited by time

Rapeseed oil

- PROS:
-- emissions similar to diesel, but CO2 cycle with plant growth closed, no SO2 and less particles
-- required space and efficiency similar to diesel
- CONS:
-- required cultivation areas not available
-- 8x more expensive than diesel fuel

E-Fuels
Fuels made of regenerativ electric power (climate neutral). CO2 from the atmosphere is merged to molecular chains.

- PROS:
-- existing infra and combustion engines can be used
-- useful when battery eletric drive is not possible (planes, ships)
-- generation in the desert
- CONS:
-- energy intense production
-- 1L e-fuel Diesel would cost 4,5€

Hydrogen

• Engine: modified gasoline engine
• Fuel: Production from water (by electrolysis), combustion to H2O, with low quantities of NOx.
  solution: water injection, lowers combustion temp. and therefore NOx. By production with solar energy: No CO2 in entire process!
  
  

- PROS:
-- no CO2 emissions
-- no toxic emission
- CONS:
-- storage
-------- gas: pressurized cylinders which is dangerous and heavy
-------- liquid: it has higher energy density than gas, but require insulation on the tank (cryogenic tank)
-------- bound in metal hydride (eg. titanium-iron)
-------- bound in form of methanol which makes it become liquid in ambient temperature, but in this case it has CO2 emissions
-------- bound in N- ethylcarbazole, it's fluid, stored without pressure, but it's toxic
-------- Absorbed in carbon nanotubes

LNG (liquified natural gas)
LNG operations are already being carried out in isolated cases in heavy commercial vehicles.

• Egine: diesel or otto engine, with otto no need of fuel, with diesel 10% of diesel fuel
• Fuel:
  -- mixture of mainly methane (98%)
  -- it's possible to use biogas or RE methane in form of LNG (bio-LNG)
  
  

- PROS:
-- clean cumbustion
-- lower fuel costs
-- drastic reduction on GHG emissions

- CONS:
-- larger tanks compared to diesel and gasoline
-- refueling cumbersome - difficult to refuel
-- fuel LNG heats up in the tank over time, increasing the pressure
-- poor infra
-- security aspects
-- CAPEX

DC with brushes
Using commutator and brushes. Not used for traction, only for accessories such as window control and windshield wipers

Alternating field machines
an alternating current flows through the windings. Due to the series connection of rotor and stator winding, both fields change their direction in the same direction, so that a uniform rotation of the rotor still results.

PM syncronous
In a synchronous machine, the rotor always follows the stator field. The speed of the rotor is therefore the same as that of the rotating field, i.e. the rotor and stator field run synchronously

• The higher the number of grooves, the smoother the torque (no ripples) because there are more sinosoids to sum up.
• Serial or parallel connection of the coils of each phase possible, depending on the available battery voltage.
• Small system voltages (48 V, 120 V)
  -- Parallel connection preferred
  -- Higher currents (for the same machine power)
• High system voltages (400 V, 800 V)
  -- Serial connection preferred
  -- Lower currents (at same machine power)
• 2 magnets in the rotor premagnetized in direction S → N
  
  
  

Even if the rotor follows the stator at the same speed, there is an angular offset depending on the load, the so-called pole wheel angle. In the unloaded state (no-load operation), the north pole of the rotor and the south pole of the stator field are exactly aligned with each other. If one increases the load on the machine, the increasing stator current generates a counter field, which leads to a rotation of the rotor relative to the stator field. The rotor thus follows the stator field with a load-dependent pole wheel angle.

• Pole wheel angle 0° to < 90° (motor operation, increases with load)
• Pole wheel angle 0° to < -90° (regenerative operation, increases with load - in direction to -90)
• Pole wheel angle = 90° or = -90°.(breakdown point of the motor, maximum power)
• Pole wheel angle < -90° or > 90°. (motor out off step, rotor can no longer follow the stator, strong torque pulsations which can damage the motor and the gearbox, must never occur.)

Separately excited synchronous machines (SESM)
The difference between a separately excited synchronous machine, also called electrically excited synchronous machine EESM, and a permanent magnet synchronous machine is the design of the rotor. The stators of both machine types do not differ. In the stator, as in the PMSM, a uniform rotating magnetic field is generated.

• Replacement of magnets by excitation coils
• Rotor field is generated by direct current (DC) in the excitation coils
  
  
  

• PROS:
• Exciter field can be adjusted independently of load and speed
• Thus, depending on the operating point, better efficiency than with PMSM possible
• Good field weakening capability → high speeds (wide speed range) possible
  
  
  

• CONS:
• Additional losses due to current in the rotor
• Thus, depending on the operating point, poorer efficiency than with PMSM is also possible
• Complicated transmission of electrical energy to the rotating rotor

Transverse flux machine
The transverse flux motor is actually an outer pole synchronous motor, but the rotating field spools are placed in peripheral direction. The magnetic flux proceeds in a meandering pattern through the stator and rotor. The drive power is generated like in every electromagnetic machine through the change of the energy density in the air gap (dW/dx).

Asynchronous machines (ASM)
The asynchronous machine also uses the same stator design as the PMSM. However, the rotor functions fundamentally differently from the PMSM or SESM.

• A large number of bars (yellow) made of a conductive material (usually aluminum or copper) are embedded in the laminated core of the rotor
• At the axial ends, the bars are connected to each other by a ring (see Fig. 3-79)
  
  
  

• Operating principle
• The rotating stator field induces a voltage in the rotor bars
• By connecting the bars at the ends, these voltages lead to currents
• The currents now generate their own magnetic field, the rotor field
• The rotor field has the same number of poles as the stator field, since it is generated by the stator field.
• The rotor is now rotated by the stator and rotor field due to the principle of magnetic attraction.
  
  

The voltage induction only works as long as the stator field and the rotor have different speeds. If the rotor turns slower, the rotor sees a changing stator field. Only then does the voltage induction work. If the rotor were rotating at the same speed as the stator field, an observer on the rotor would always see the same stator field. However, since no voltage is induced without a change in the field and thus no current can flow in the rotor, the rotor would lose its magnetic field and consenquentlu could not be pulled along further by the stator field. Therefore, the rotor must always turn a little slower than the stator fifeld. This speed difference is called slip s. It indicates the percentage of deviation of the rotor speed n from the speed of the stator field n1

• Idle speed - slip-s ~= 0
• With load - slip increases successively with load. Continuous operation with slip from 3 to 10%. Max torque (breakdown torque) s~=20%. A further increase in torque over the breakdown torque causes the machine to stop. However, this is prevented in controlled traction drives by the power electronics.
  
  

Since an asynchronous machine does not contain any magnets, no voltage is generated at open terminals when it is rotated from the outside. In order to operate the machine as a generator nevertheless, a rotary voltage must always be applied. Only then a field is also generated and a current can be driven back into the battery. Recuperation is therefore only possible with an external voltage source. Since this is always provided in the car by the battery, there are no disadvantages here compared with the other machine types.

Switched reluctance machine
The reluctance machines have different numbers of teeth on rotor and stator. The rotor consists of a sheet metal package that forms some kind of gear. The teeth of the stator are winded with spools and carry a current. Through the current, a cog of the rotor is pulled to a cog of the stator which carries the current. By switching certain teeth on and off, the rotor starts to turn.

• Stator
• Designed as a hollow cylinder (stator yoke with teeth)
• Consists of laminated, electrically insulated sheets (usually 0.2 to 1.0 mm thick)
• The winding of copper wire is located in the grooves
• Surrounded by a housing
• Housing takes over the cooling
  
  • Air cooling
  • Liquid cooling (mostly spiral cooling channels)

• Distributed windings
• The coil sides of the three phases are evenly distributed over the slots
• The windings of one coil exit at the end of the stack of laminations and reenter on the
  opposite side
• The coil width depends on the number of poles
  
  
  

• PROS:
• Magnetic field in air gap is sinusoidal
• Number of poles freely selectable = independent of the number of grooves
  
  
  

• CONS:
• Complex manufacturing → higher costs
• Very difficult to automate depending on the design
• Large winding heads (= a lot of installation space)

• Concentrated windings
• Each coil is wound around one tooth at a time
• Also called single tooth winding
  
  
  

• PROS:
• Compact winding head, space saving
• Simple construction
• Simple manufacturing
• Cost effective
  
  
  

• CONS
• Coil width = distance between two grooves
• For electromagnetic reasons, the coil width should correspond approximately to the pole
  width
  
  • Larger machine diameter = more teeth
  • More magnetic poles necessary
  • Speed and thus power density decreases
• Magnetic field in the air gap is strongly distorted (= many harmonics)
  
  • Harmonics on torque more pronounced
  • Stronger noise excitation, machine becomes louder

Formed coil windings
In traction drives, so-called shaped coil windings have been used more and more frequently in recent years. These represent a compromise between distributed windings and single-tooth windings and attempt to combine the advantages of both types:
STRUCTURE: Winding consists of individual, preformed rectangular conductors. Preformed wire pieces are pushed into the grooves from one side. Bending of the wires on the other side of the stator. Welding (= interconnection to form coils). Between 2 and 8 conductors per groove. 4 variants: Hairpin, D-pin, I-pin and wave winding.

• PROS
• Manufacturing can be fully automated
• Same good electromagnetic properties as distributed windings
  
  
  

• CONS
• Only economical from higher quantities (costly tools for forming the wires)
• Low flexibility with regard to changing the number of windings
• Only practicable for mass production in automotive segment

• Asynchronous machine
• Internal bars are inserted into the rotor by die casting and directly connected by shorting ring (especially with aluminum).
• Other possibility: hammer in copper bars and weld them with attached end rings (e.g. Tesla Motors)

• Permanent magnet synchronous machines

• TYPE I

  
  
  • Mostly used in starter generators and transmission-integrated machines
  • Primarily used in hybrid vehicles
  • Cost effective
  • Plenty of space inside the rotor (for clutches, etc.)
    

• TYPE V

  
  
  • Application in powerful main drives
  • Variants with multiple layers of magnets possible
    

• TYPE U

  
  
  • Similar to V-arrangement, with further magnet in the middle
  • Same points as V

Crash safety:

• Corrosion resistant, crash proof battery housing
• System to discharge reaction gases in case of malfunction
• Controlled discharge reaction of cell for the case of a destroyed separator (nail test)

Operation safety:

• Cell monitoring, automatic disable before crossing critical threshold value
• Thermo management (cold start properties)
• Safety against overcharging
• Cell balancing

Service safety:

• Cable labeling
• Contact protection (isolation, plug)
• Partition in partial batteries with connecting safety switches

Function
Electrons flux from anode (-) to cathode (+) making the ions of lithium to flow through the electrolyte towards the graphine

Structure
Example PEM – cell (Proton Exchange Membrane or Polymer Electrolyte Membrane)
Sandwich contruction:

• 1 - Electrolyte: 0,1 mm thick plastic membrane, proton permeable, located in center of cell. On both sides catalytic coating (Platinum).
• 2 - Electrodes: Graphite paper, on both sides of electrolytes, permeable to gas.
• 3 - Bipolar plates: Graphite, outer layer of cell. Channels milled in, on one side loaded with hydrogen, on other side with oxygen (air).

Function
Cell reaction -> 1H2 + O2 —> 2H2O

• H2: Ionized on platinum catalyst, protons develop (cores of hydrogen atoms)
  and electrons.
  
  • Protons travel through PEM – layer to opposite side.
  • Protons charge electrode on the oxygen side positively (electric plus pole)
  • Electrons charge electrode on the hydrogen side negatively (electric minus pole).
• O2: O2 absorbs electrons from H2, the following appear
  
  • Negatively charged oxygen ions,
• H2O: H2 protons and negatively charged O2-Ions bond to electric neutral H2O molecules.
• Consumer: Proton migration creates a difference in voltage between the electrodes. Pooling of cells to stacks

Fuel

• Hydrogen, production from H2O: through electrolysis, energy therefore from wind, solar or nuclear energy. Problems with refueling
  
  
  

• Hydrogen, Production from Methanol (CH4O) in reformer: Reformer can be placed in vehicle, Refueling (liquid at normal temperature) uncritical,Energy requirement for reformer from fuel cell. Problems: CH4O from fossil energy sources (natural gases) or biomass (closed cycle) or from hydrogen + CO2 (under high pressure and high temperature, CH4O is created as H2 carrier)
  
  
  

• Hydrogen, production from gasification of biomass (efficiency 69-78%). Good because there no toxic emissions and it has better efficiencies than current combustion engines

Potential

• Sunshines⊥, skyclear, Irradiation 1000W/m2
• Efficiency of normal solar cells, depending on type: 17-25%
• Power output ~20%
• Daily driving distance around 4km and up to 24 with additional battery

Production of solar cell energy intensive, high "energy payback time"