48 V Traction Drives for the BEV Mass Market

Transcription

1 48 V Traction Drives for the BEV Mass Market Dieter Gerling Universität der Bundeswehr München

2 48 V Traction Drives for the BEV Mass Market development of costs for battery packs estimated for Tesla Model S estimated for Chevy Bolt estimated for Tesla Model 3 (Gigafactory) 2

3 standard system up to now for high power traction = 3 M ca. 375V ca. 150V 3

4 possible system architecture with low voltage DC circuit M battery 48V DC electrical system power electronics electrical machine 4

5 stator winding evolution distributed winding concentrated winding stator cage winding Quelle: derkonstrukteur.de 5

6 48 V Traction Drives for the BEV Mass Market building the entire electrical drive no more coils, massive stator cage instead perfect utilization of available space: perfect slot filling factor no end-windings great thermal behavior low thermal resistance bar iron water cooled end-ring possible minimum production cost aluminum instead of copper simple production, e.g. die-casting, low invest extremely smooth rotating field individual bar currents very high efficiency 6

7 ISCAD (Intelligent Stator Cage Drive) e.g. as induction motor with changing number of poles during operation 7

8 changing the number of pole pairs during operation (exemplary calculation) p=3 p=2 p=1 8

9 best-in-class overload capability This overload area can be used by ISCAD (machine and power electronics) because the voltage limit is not reached 9

10 ISCAD: power electronics generations Gen 1 Gen 2 Gen 3 10

11 48 V Traction Drives for the BEV Mass Market power electronics: losses at partial load advantages of MOSFETs in relevant driving cycles lower forward voltage at partial load ( instead ) Ă Ă further optimization potential for MOSFET inverter 11

12 DC wiring larger cross-sections for higher currents short distances for light-weight, aluminum instead of copper 300 hp example (5 ka) distance: 1 meter material cost: < 5 conductor mass: < 5 kg large contact surface flexible coax conductors using metal braid compact design perfect shielding of electromagnetic fields 12

13 top class efficiency 48 V Traction Drives for the BEV Mass Market Evaluation of Machine and Inverter Losses NEDC WLTC ISCAD Improves Efficiency by 20% to 25% 13

14 top class efficiency 48 V Traction Drives for the BEV Mass Market 14

15 low power charging (up to 22kW) similar to high-voltage systems reduced cost high power charging (up to 350kW) currently no existing solution or infrastructure for 48V technically feasible DC/DC converter with current infrastructure 1) conductive: contacts with large cross section, i.e. low ohmic resistance wireless (inductive): currently under investigation 15 1) Example by Fraunhofer and Panasonic: 200kW in 1.4 litre (2014)

16 numerous additional advantages MOTOR SYSTEM extremely cost-efficient no supply issues (copper, magnets) extremely robust electrically intrinsic safe system effort for high-voltage training of employees (R&D, production, maintenance, etc.) is avoided 12V-supply is simple and very costefficient (low voltage DC/DC-converter) scalability of the system is very simple (same power electronics modules for all different power levels) best-in-class availability very low system costs 16 POWER ELECTRONICS BATTERY drop out of single half-bridges does not result in large power reduction power electronics and electrical machine are perfectly integrable high switching frequency improved EMI characteristics common cooling with electrical motor drop out of single battery cells does not result in large capacity reduction simplified BMS simplified CID increased available capacity and lifetime (against higher voltages)

17 Conventional BEVs ISCAD 48V Drive NO DANGER LOW VOLTAGE SUITABLE FOR ANYBODY 17