HEV: combination of ECEN507 Lecture 0: HEV & Series HEV HEVs and PHEVs a gasoline powered internal combustion engine (ICE) or an alternative power (e.g. fuel cell) electric drives: electric machines and power electronics relatively small energy storage system (e.g. battery) HEV efficiency improvements Regenerative braking ICE operated around the most efficient operating point, not directly tied to the required drive power & speed Downsizing : a smaller ICE, optimized for narrower operating range No idling required when the vehicle stops, keep ICE off PHEV: HEV with a larger battery to allow EV operation over a distance ( all electric range AER) CU Boulder ECEN507, USU ECE 5930
HEV Architectures CU Boulder ECEN507, USU ECE 5930
Series HEV drive train In a PHEV, a (larger) battery can be charged from the electric power grid v F v Fuel ICE n T ED Battery charging (alternator) ICE starting V DC Battery Energy storage ED Traction Regenerative braking n T Transmission Wheels (radius r v ) n v T v Example: Chevy Volt, a PHEV with a drive train based on the series architecture: 6 kw (83 hp,.4 L) ICE 55 kw electric drive ED kw (49 hp) electric drive ED CU Boulder ECEN507, USU ECE 5930 3
Series HEV Advantages ICE mechanically decoupled from the traction drive, can be operated over a narrow range of operating points to maximize efficiency ICE can be downsized, since it only needs to supply average, not peak traction power demand CU Boulder ECEN507, USU ECE 5930 4
Series HEV component sizing Traction electric drive ED sized based on acceleration performance (same as EV electric drive) Engine power rating must be greater than the power required for cruising at constant speed for long periods of time Energy storage system Power: must be greater than the difference between traction ED and charging ED power rating Energy: based on E (depends on the cycle), and SOC (based on battery cycle life) CU Boulder ECEN507, USU ECE 5930 5
Example v F v Fuel ICE n T ED Battery charging (alternator) ICE starting V DC Battery Energy storage ED Traction Regenerative braking n T Transmission Wheels (radius r v ) n v T v CU Boulder ECEN507, USU ECE 5930 6
Traction (ED) sizing v F v Fuel ICE n T ED Battery charging (alternator) ICE starting V DC Battery Energy storage ED Traction Regenerative braking n T Transmission Wheels (radius r v ) n v T v CU Boulder ECEN507, USU ECE 5930 7
ICE and ED sizing v F v Fuel ICE n T ED Battery charging (alternator) ICE starting V DC Battery Energy storage ED Traction Regenerative braking n T Transmission Wheels (radius r v ) n v T v CU Boulder ECEN507, USU ECE 5930 8
Series HEV Disadvantages Power from the ICE is converted twice, through ED and ED Traction electric drive ED must be rated at peak power, while the ICE adds cost and weight CU Boulder ECEN507, USU ECE 5930 9
Energy storage sizing: power v F v Fuel ICE n T ED Battery charging (alternator) ICE starting V DC Battery Energy storage ED Traction Regenerative braking n T Transmission Wheels (radius r v ) n v T v CU Boulder ECEN507, USU ECE 5930 0
Energy storage sizing: energy v F v Fuel ICE n T ED Battery charging (alternator) ICE starting V DC Battery Energy storage ED Traction Regenerative braking n T Transmission Wheels (radius r v ) n v T v CU Boulder ECEN507, USU ECE 5930
HEV battery sizing: US06 driving cycle 00 80 Prius sized vehicle example v [mph] 60 40 0 0 0 00 00 300 400 500 600 time [s] 00 P v [kw] 50 0-50 0 00 00 300 400 500 600 time [s] Average power P vavg supplied by the ICE P = P v P vavg supplied by the electric drive and battery E [kwh] 0.6 0.4 0. CU Boulder ECEN507, USU ECE 5930 0 t E P( ) d 0-0. 0 00 00 300 400 500 600 time [s] SOC min 0.5 kwh SOC max A relatively small battery is sufficient
Series HEV system control v F v Fuel ICE n T ED Battery charging (alternator) ICE starting V DC Battery Energy storage ED Traction Regenerative braking n T Transmission Wheels (radius r v ) n v T v Objectives: Meet the demand by the driver Operate each component with optimal efficiency Recapture braking energy Maintain the state of charge (SOC) of the energy storage system (battery) in a preset window CU Boulder ECEN507, USU ECE 5930 3
ICE Efficiency Map CU Boulder ECEN507, USU ECE 5930 4
ON/OFF ICE Control Strategy ( Thermometer or Bang Bang control) CU Boulder ECEN507, USU ECE 5930 5
Series HEV system control v F v Fuel ICE n T ED Battery charging (alternator) ICE starting V DC Battery Energy storage ED Traction Regenerative braking n T Transmission Wheels (radius r v ) n v T v CU Boulder ECEN507, USU ECE 5930 6
Example of operation CU Boulder ECEN507, USU ECE 5930 7