ORNL Researchers Modify Plug-in Hybrid Electric Traction Drive Power Electronics to Function as On-Board Charger; Mobile Power Generation and V2G Support as Well
Researchers at the Department of Energy’s Oak Ridge National Laboratory have designed, fabricated and demonstrated a PHEV traction drive power electronics system that functions as the on-board charger, and that also provides significant mobile power generation and vehicle-to-grid support capabilities.
The system comprises a 55 kW motor inverter and a 30 kW generator inverter that is capable of Level 1 and Level 2 charging rates (1.8 ~ 19.2 kW), mobile power generation of up to 20 kW, and vehicle-to-grid support. The system, if applied in a vehicle, could represent up to a 90% reduction in cost and volume compared to on-board standalone battery chargers.
The new technology eliminates the separate charging mechanism typically used in PHEVs, reducing both cost and volume under the hood. The PHEV’s traction drive system is used to charge the battery, power the vehicle and enable its mobile energy source capabilities.
—Dr. Gui-Jia Su, Senior R&D Staff Member, Lead Engineer of Power Electronics
|FY08 prototype test setup. Source: Su. Click to enlarge.|
The approach, said Su, is to utilize on-board inverters and motors for charging/sourcing; no additional switch or filter inductor components are required. “It’s basically software and pulling some more wire,” Su said.
The two motors need not be rated at the same power level, and the approach can be applied to a range of motor/power electronics capabilities. The current rating of the switches and the motors is what determines the charging rate.
Testing of the charging system showed a high efficiency of 92~98% vs. 80~85% for commercial, off-the-shelf (COTS) charges. The system support a power factor of >98% and low harmonic distortion.
Su said that several companies, including Raser and MBTech, have expressed interest in the system.
Utilizing the Traction Drive Power Electronics System to Provide Plug-in Capability for PHEVs (Su, DOE Merit Review, 2009)
Lixin Tang and Gui-Jia Su (2009) A low-cost, digitally-controlled charger for plug-in hybrid electric vehicles. IEEE Energy Conversion Congress and Exposition (ECCE 2009), pp. 3923 - 3929 doi: 10.1109/ECCE.2009.5316496
Gui-Jia Su and Lixin Tang (2010) Control of Plug-in Hybrid Electric Vehicles for Mobile Power Generation and Grid Support Applications. APEC 2010