Hybrid Drive Systems for Vehicles

Transcription

1 Hybrid Drive Systems for Vehicles More on Auxilliary Systems and EMC

2 Auxiliary system energy consumption 24 V System, 1170 W Subsystem energy usage, 4 kw Losses in battery 24% Lights 25% Cooling Fans 31% 24V DC/DC 29% Control system 51% Compressor 21% Water pump 5% Servo pump 14% Air (compressor) system, 830 W Suspension System 32% Door Opening 35% Brake 15% Hand Brake 18%

3 Air pressure driven loads Brakes Suspension Door opening 1 Brakes 2 Electronic control system 1 3 Valves 4 Air dryer 5 Compressor

4 New technology selection Pneumatic (air) system, 830 W Pneumatic (air) system, 830 W System Pneum [W] El [W] Suspension Suspension 32% 32% Door Opening Door Opening 35% 35% Doors Suspension Brake 15% Brake 15% Parking Brake 18% Parking Brake 18% Parkering Brake

5 Auxiliary [kw] Power [kw] Propulsion [kw] Speed [km/h] Control Peak Shaving seconds seconds AC DC/DC Propulsion 10 AC+DC/DC+Propulsion Run at 260 full 260 power seconds 400 seconds

6 AC-system on/off condition duty cycle generator Power [kw] off - on Propulsion power Power limits normal operation off-peak power limit on-controller on-regen. power limit offcontroller Reference Actual time

7 Potential improvements of the auxiliary system Fuel allocation [%] Potential improvements Auxiliary system Propulsion system Hybrid bus Conventional bus

8 Conventional electric loads Electric generator load in average 600 W Assume efficiency 50 % Mechanical Generator load 1200 W

9 Drag powers... Remember generator load 1.2 kw!

10 Additional loads... Weight, volume and efficiency benefits in electrical drive of traditionally mechanically driven loads. Many more could be added: Electric compartment heating, GPS Navigation Systems, DVD based Passenger Entertainment Systems, BlueTooth connection for giving brought on Mobile Phones Hands free via the Sound Systems, Detachable Cooling Boxes, Electrically Operated Foldable Cabriolet Roof, Electrically Controlled Suspension and Levelling System, Reversing Distance Sensing System, 230 V/50 Hz outlet for electric power to e.g. electric hand tools or electric grills for tail gate parties

11 48 V this time

12 CO2 and Load Migration

13 Different Voltages

14

15 High voltage? > 1.5 V > 15 V > 50 V > 150 V > 300 V > 3 kv > 50 V is regarded as high 48 V common 36/42 V

16 What is a dangerous equipment? Equipment where a fault can cause harm to a person or property. 12 V system can also be dangerous Can cause fire Hydrogen explosion possible Even if the voltage is low, the short circuit current is high and thus also the possible heat dissipation

17 Toyota Prius safety system

18 Basic dangers 1. Direct current through body 2. Short circuit current that cannot be interrupted 3. High output voltage from switching converters Also EMC 4. Parasitic currents from switching converters 5. Fire or explosion

19 Current through body Current depends on Voltage AC, especially 50 Hz, is worst But, DC is also dangerous Resistance Skin + body fluid. Skin most important Moisturous skin worst. Murare... > 80 ma in more than 0.2 seconds can lead to cardiac arrest

20 Approximate values for body sensitivity to current

21 Body Resistance Dry Skin, Hand-to-Hand resistance=100 kohm 3000 Wet or broken skin, Hand-to-Hand resistance < 1000 Ohms Kroppens inre resistans i Ohm V 1000 V Ström genom kroppen i Ampere Conclusion on contact: 0.4 Already at 125 V is life threatening! 400 V is VERY DANGEROUS! Spänning i Volt

22 Thus: Have the greatest respect for the traction battery! It is dangerous!

23 Short circuit current Very large short circuit currents Low inner resistance Several 1000 Ampére short circuit current Difficult to interrupt due to the inductance of the cables and the lack of zero crossings

24 Inductance Stored energy in the magnetic field. Unit is Henry Single conductor, 1 mikrohenry/m Equation u=l*di/dt What does that mean?

25 To breake an inductive current The inductance sets up a voltage to keep the current going. Arcs Used in ignition coils and in light tube igniters

26 Light tube Lysrör Glimtändare Induktor u nät Bimetallkontakt - Glimlampa

27 Electric strength of air 3 MV/m Whe the air is ionized the temperature reaches several 1000 C in a plasma with strong light Burns Eyes damaged Used in welding

28 Conclusions on braking an inductive current: Very large voltages are created that may start sparcs. Use fuses, protective clothing, fire extinguisher Don t let it happen!

29 Power Electronics To convert electric energy Range: MW Switching amplifiers

30 Why Switch? Traditional converters have low efficiency, e.g %. Switching converters >95 %.

31 Classes A B och AB 20 25% 60 %

32 Class D Audio Amplifiers

33 Modulation PWM Spänning Bärvåg Pulsad utspänning Önskad spänning till last Tid Verklig spänning till last Tid

34 PWM A variable voltage is created with a pulse width / pulse period. Bärvåg Pulsad utspänning Önskad spänning till last Verklig till last Tid

35 PWM in Car Long cables Square voltages contain wide spectrum Noise generated Can be heard in the radio...

36 PWM va*, vb* & um va*, vb* & um sa va va 200 va

37 4-Quadrant DC converter All combinations of u and I +Ud/2 -Ud/2 0 id sa i va L, R + u - + e - - vb sb

38 4Q PWM : II 200 va*, vb* & um va vb u

39 3-phase +Ud/2 id 0 sa va sb vb sc vc -Ud/2 + uab - + ubc - - uca ua ub uc - - vo -

40 Control of 3 phase converters. Symmetric references varef tri ua r ef & tri v v v u * a * b * c z * a * b * c u uz u uz u uz max min va va vo v ua u=va-v0 grundton 50 Hz

41 Ex: UPS (Uninterruptable Power Supply) Likriktning Likspänningsomvandling 1 Likspänningsomvandling 2 Växelriktning + unät - Batteri + u - last

42 Conclusions on PWM Even if the average value of the voltage is low, the instantaneous value can be high!

43 EMC : I Electro Magnetic Compatibility Coexistence of electric and electronic systems Coexistence of the vehicle and sourrounding world Connecting media: Conductive. E.g. Rectification noise from the generator Inductive and Capacitive. E.g. Between cables in the same bundle

44 Parasitic currents Common mode phenomenon Galvanic isolation

45 This is what you think it looks like Resistor Batteri Induktor

46 and with some experience maybe like this Resistor Batteri Induktor Parasitic components in conductors and circuit board

47 but in reality like this! Resistor Batteri Induktor Internal non ideal compoents added

48 EMC problems with PWM Batteri Kraftelektronisk omvandlare Last

49 Ex: Battery and Motor Capacitance to Chassie 12 V 42 V 300 V Gen FAS chassie

50 Ex: Battery and Motor capacitance to chassie... " 0 V" Obs AC voltage across the parasitic capacitances, with 300 V amplitude and switching frequency!!!! " -300 V" " 0V" " 0V" " 0V" chassie

51 Communication in this environment RDU control computer Vehicle control computer 12 V 42 V 300 V Gen FAS chassie

52 Line Charging systems 1-phase, 10 A = 2.3 kw = 20 km driving distance charged per hour (=speed!) 3-phase, 16 A = 11 kw = km driving distance charge per hour

53 Example of a line charger Phase voltages a 0 Optional transformer Positive battery potential Negative battery potential Phase Inductances Motor Conv reconected battery cha b c

54 Auxiliary Power Unit (APU) : 1 Heavy vehicles at rest. Driver living in the vehicle. Consuming low amounts of electric energy. Energy provided via Diesel Engine at very low power. E.g. A 300 kw diesel providing 3 kw of electric power. Too low efficiency.

55 APU : II Separate system: Fuel Cell based Hybrid drive system battery Example: 400 kw Diesel, max efficiency 44 % Can 20 kw with 40 % efficiency 5 kwh NiMH battery (50 kg) SOC variation allowed to be 40 % 2 kw load: 1 hour pure battery operation minutes recharging from 20 kw / 40 % eff. Assume 85 % charge efficiency -> 40*0.85 = 34 % Probably 10 % less than Fuel Cell, but Hybrid drive benefits and single fuel.